What doctrines are absolutely essential to Christianity? As the Word of God, all Scripture is equally and absolutely authoritative. But not all Scripture is equally clear, nor equally central to salvation. Christians disagree on certain nuanced details, yet are united by our common salvation by God’s grace through faith in Christ. On the other hand, there are people who profess to be Christians, but who deny central, core doctrines of the faith. Where is the line that divides genuine faith from a false faith? At what point does theological error become heresy?
Heresy is defined as “adherence to a religious opinion contrary to church dogma” or “an opinion, doctrine, or practice contrary to the truth or to generally accepted beliefs or standards.” The problem with using such definitions is that different churches themselves disagree on some issues of doctrine. Even individuals within the same local church may disagree on what is “generally accepted.” Perhaps the word ‘heresy’ ought to be reserved for the most serious of theological errors – those that deny an essential aspect of the Gospel. Then we can define ‘heresy’ as a theological error so severe that it indicates that a professing Christian might not be truly saved.
Since we are saved by grace and not by our merit, God will no doubt forgive some of our theological shortcomings – places where our thinking does not currently align with Scripture. But when a person denies certain core aspects of the Gospel, this indicates that he or she has not been granted saving faith in Christ. The Bible itself teaches that certain core doctrines cannot be rejected by a saved person. Let’s examine these.
1. The Deity of Jesus Christ
The Bible not only teaches that Jesus is God, but it also teaches that anyone who denies this core principle is not saved. Professing that Jesus is Lord (Yahweh) is necessarily associated with salvation according to Romans 10:9-13. Verse 9 gives two conditions that must accompany salvation; the first is that a person must confess with his mouth that Jesus is Lord. The author (Paul) then proceeds to prove that this is a necessary condition by quoting Joel 2:32 in Romans 10:13, “For whoever will call on the name of the Lord will be saved.” Jesus is the Lord, and professing this with the mouth is thus necessary to demonstrate that a person’s faith in Him is genuine.
The critic may object, “But couldn’t this just mean that Jesus is a lord, not the Lord God?” No. Context shows that the word “Lord” is being used here to refer to Yahweh, the almighty God. Paul cited Joel 2:32 in his proof that calling upon the name of the Lord is necessary for salvation. And the word translated “Lord” in Joel 2:32 is Yahweh – the unique name of God. Paul is therefore claiming that those who call upon Jesus as Yahweh will be saved.
Jesus Himself said as much in His earthly ministry. In John 8:24, Jesus said, “for unless you believe that I am, you will die in your sins.” Some English translations add the word “He” as in “I am He.” But in fact, this word is absent in the original Greek text. Jesus was actually saying that people would die in sin (unsaved) unless they believe that He is the “I am.” The “I am” is one of the names of the Holy God, first used in Exodus 3:14, and then later in Isaiah [e.g. Isaiah 43:10, 25, 45:18, 46:4]. Jesus refers to Himself as the “I am” again in the same chapter: “Jesus said to them, ‘Truly, truly, I say to you, before Abraham was born, I am’” (John 8:58). The strange grammatical construction shows that Jesus is indeed applying one of the names of Yahweh to Himself. It would be blasphemy if Jesus were not in fact God.
God the Father refers to Jesus as “God” in Hebrews 1:8-12. Hebrews 1:8 states, “But of the Son He says, ‘Your throne, O God, is forever and ever, and the righteous scepter is the scepter of His kingdom.” Here, the Lord quotes Old Testament passages describing Yahweh, and applies them specifically to Christ (compare Psalm 102:1,24-27). The Lord God says in Isaiah 45:23 that “to Me every knee will bow, every tongue will swear.” In Philippians 2:10-11, Paul explains that this was Jesus speaking: that to Jesus “every knee will bow” and “every tongue will confess.” That’s because Jesus is the Lord God.
Yet, unsaved people cannot accept and embrace that Jesus is God. A genuine saving faith that Jesus is the Lord is something only the Holy Spirit can give (1 Corinthians 12:3). Thus, a rejection of the divine nature of Jesus Christ is an indication that a person is not (as yet) saved (John 10:25-30).
2. The Resurrection of Christ
The other criterion for salvation that Paul gives in Romans 10:9-10 is that a saved person must believe that God raised Christ from the dead. The resurrection of Christ shows that He has authority over life and death (John 10:17-18). It establishes that what He said about Himself is true. According to the Apostle Paul, faith that Christ rose from the dead is what results in (imputed) righteousness (Romans 10:9-11).
Resurrection means being raised up from the dead – going from a state of death to a state of life. But there is an important caveat to consider when discussing life, death, and resurrection. The Bible speaks of two types of life, two types of death, and therefore two types of resurrection. On the one hand, there is physical life, death, and resurrection. And on the other hand, there is spiritual life, death, and resurrection. Physical life, death, and resurrection all pertain to the physical functioning (or lack thereof) of physical bodies. A person is physically alive when his heart is beating, blood is flowing, and so on. When those functions cease, a person dies. The Bible speaks of the physical resurrection of several individuals, such as Lazarus (John 11:14-45), and Jesus Himself (Matthew 28:6-7).
Spiritual life and death both pertain to the state of a person’s immaterial spirit. God designed humans to love Him and obey His commandments. This is the function of a living spirit. When Adam sinned against God, his spirit “died” in the sense that it no longer sought to live for God, but for sin. Adam’s descendants have inherited a dead spirit and do not seek after God (Ephesians 2:1). However, God has mercy on some and resurrects their dead spirit, resulting in spiritual life (Ephesians 2:5-6). All true believers have already experienced this spiritual resurrection.
Jesus spoke of the difference between these two resurrections in John 5:24-29. He first addresses spiritual resurrection: “Truly, truly, I say to you, he who hears My word, and believes Him who sent Me, has eternal life, and does not come into judgment, but has passed out of death into life” (John 5:24). This spiritual resurrection is applied to everyone who trusts in Christ for salvation, and only them. Thus, the Lord says in John 5:25, “Truly, truly, I say to you, an hour is coming and now is, when the dead will hear the voice of the Son of God, and those who hear will live.” Notice that Jesus indicates that this spiritual resurrection (1) applies only to some – “those who hear,” and (2) takes place both in the present and also in the future – “an hour is coming and now is.”
Then Jesus describes the physical resurrection of the dead in John 5:28-29 which states, “Do not marvel at this; for an hour is coming, in which all who are in the tombs will hear His voice, and will come forth; those who did the good deeds to a resurrection of life, those who committed the evil deeds to a resurrection of judgment.” To clarify that He is speaking of the physically dead, He refers to them as those “who are in the tombs.” Those would be physical bodies of course.
This physical resurrection differs from spiritual resurrection in two ways. First, it applies to everyone who has ever died – “all who are in the tombs will hear His voice and will come forth.” Second, it is entirely in the future: “an hour is coming” (but not “and now is”). Thus, Jesus indicates that there will be a time in the future when everyone who has ever died will be resurrected. Jesus said that this general resurrection will occur on the “last day” (John 6:39, 40, 44, 54). This indicates that temporal history will end at some point, ushering in the eternal state.
So, which of these two resurrections did Christ experience? Clearly, Jesus rose from the dead physically. Unlike all other men, Jesus never experienced spiritual death because He never rebelled against God (Hebrews 4:15; 2 Corinthians 5:21). Christ obeyed His heavenly father perfectly and never needed any sort of spiritual resurrection because He was never “dead in sins.” Moreover, Jesus physically died by crucifixion (Mark 15:24; Luke 23:46), and was therefore physically raised on the third day (1 Corinthians 15:4; Acts 10:40). He claimed that His physical body was proof of His bodily resurrection (Luke 24:39).
Therefore, it is a belief in the literal, physical, bodily resurrection of Christ that is necessary for salvation (Romans 10:9-10). Those who believe that the resurrection of Christ is merely a spiritual resurrection, or otherwise non-literal, do not have salvation. The physical resurrection of the dead is an essential part of the Gospel. The Bible says, “But if there is no resurrection of the dead, not even Christ has been raised; and if Christ has not been raised, then our preaching is vain, your faith also is vain. Moreover we are even found to be false witnesses of God, because we testified against God that He raised Christ, whom He did not raise, if in fact the dead are not raised. For if the dead are not raised, not even Christ has been raised; and if Christ has not been raised, your faith is worthless; you are still in your sins” (1 Corinthians 15:13-17. Hence, the resurrection of Christ is essential to the Gospel. Anyone who rejects that Christ physically rose again does not have salvation.
3. The General Resurrection
The resurrection of Christ foreshadows the future resurrection of all the dead. 1 Corinthians 15:20 states, “But now Christ has been raised from the dead, the first fruits of those who are asleep.” In the Old Testament administration, the Israelites celebrated the Festival of First Fruits after Passover. In this festival, they offered a sheaf of the first fruits of their first crop to the Lord (Leviticus 23:9-11). This showed the gratitude of the people toward God who provides the harvest. And it also shows their trust that God would also bring forth the rest of the harvest in time. That is, if God was faithful to bring forth the first fruits, then He will be faithful to bring forth the rest of the harvest in season.
Thus, the Apostle Paul argues in 1 Corinthians 15:20 that Christ’s resurrection is the first fruits of the general resurrection. That is, if God was faithful to raise Christ, then He will be faithful to raise everyone else on the last day (John 6:40, 44, 54). This general resurrection is described in 1 Corinthians 15:22-26 which states, “For as in Adam all die, so also in Christ all will be made alive. But each in his own order: Christ the first fruits, after that those who are Christ’s at His coming, then comes the end, when He hands over the kingdom to the God and Father, when He has abolished all rule and all authority and power. For He must reign until He has put all His enemies under His feet. The last enemy that will be abolished is death.”
Christ will abolish death by undoing it; He will resurrect everyone who has ever died. They will be physically raised just as Jesus was. And according to Scripture, this will occur on the last day, thereby ushering in the eternal state.
The strong connection between Christ’s resurrection (as the first fruits) and the general resurrection (the final harvest) is what makes this a Gospel issue. The Scriptures say, “and if Christ has not been raised, your faith is worthless; you are still in your sins. Then those also who have fallen asleep in Christ have perished” (1 Corinthians 15:17-18). That is, there would be no hope of the general resurrection if Christ had not been raised from the dead.
If there were no general resurrection in our future, then Christ could not have been raised. It was His resurrection as the first fruits that guarantees the general resurrection. Thus, a denial of the future general physical resurrection of all the dead is heresy because it implicitly denies the bodily resurrection of Christ. And we saw previously that belief in Christ’s resurrection is essential for salvation.
As the Apostle Paul explained, “Now if Christ is preached, that He has been raised from the dead, how do some among you say that there is no resurrection of the dead? But if there is no resurrection of the dead, not even Christ has been raised; and if Christ has not been raised, then our preaching is vain, your faith also is vain” (1 Corinthians 15:12-14).
This is why full preterism is heresy. The full preterist, also known as a hyperpreterist, or (somewhat inaccurately) a consistent preterist, is one who believes that all biblical prophecies have been fulfilled. Usually, full preterists believe that all the prophecies concerning the second coming of Christ were fulfilled in A.D. 70. Although a case can be made that God did indeed come spiritually in judgment when Jerusalem was sacked and the Temple destroyed in A.D. 70, clearly this event did not end temporal history. Neither did it abolish death, nor see a resurrection of all the dead, nor usher in the eternal state.
Since there was no physical resurrection of all people in A.D. 70, the full preterist usually interprets all references to the resurrection as a spiritual resurrection, not a physical, bodily resurrection. But if Christ is the first fruits of those who are raised, and their resurrection was spiritual, then this implies that Christ’s resurrection was merely spiritual, and not bodily/physical. But we have already seen that our salvation depends on the physical, bodily death and resurrection of Christ.
Therefore, any position that denies the future physical return of Christ and the resurrection of the dead that accompanies it is necessarily heretical. Some people deny this essential doctrine without embracing all the other tenets of full preterism. But our salvation hinges upon our faith in the literal, bodily resurrection of Christ as the first fruits of all those who will be resurrected (Romans 10:9-10; 1 Corinthians 15:12-26).
Full preterism should not be confused with “partial preterism.” The latter is compatible with essential Christian doctrines and embraces the future coming of Christ and the resurrection of the dead. Partial preterism is the position that many prophesies in Scripture have already been fulfilled, but that some will be fulfilled in the future. In a sense, all genuine Christians are partial preterists (although not all adopt the label) because we all accept that the Old Testament prophecies concerning the first coming of Christ are now fulfilled. Yet we await the future physical return of Christ and the resurrection of the dead with great hope and eager expectation. Brothers and sisters in Christ may disagree on whether a specific prophecy has yet to be fulfilled. But the future general resurrection and Christ’s past resurrection as the first fruits of it are non-negotiables.
It appears that Paul’s comments in 2 Timothy 2:18 were to refute an early form of full preterism. Namely, he refers to “men who have gone astray from the truth saying that the resurrection has already taken place, and they upset the faith of some.” The full preterist might point out that this epistle was written before the events of A.D. 70. And yet, Paul’s argument is still sound. We have not observed a general resurrection from the dead, nor the abolishment of death, and therefore these things are yet to occur. Many Scriptures confirm that the resurrection and the abolishment of death will happen on “the last day” (John 6:40, 44, 54; 1 Corinthians 15:22-26).
4. The Gospel: Salvation by Grace Through Faith in Christ
Since the fall of Adam into sin, there has been exactly one way to be reconciled to God. This salvation is and always has been by God’s grace received through faith in the Messiah. “For by grace you have been saved through faith; and that not of yourselves, it is the gift of God” (Ephesians 2:8). No one has ever been saved by good works. “Not as a result of works, so that no one may boast” (Ephesians 2:0). “He saved us, not on the basis of deeds which we have done in righteousness, but according to His mercy, by the washing of regeneration and renewing by the Holy Spirit” (Titus 3:5).
Sometimes people get the impression that Old Testament believers were saved by works or by animal sacrifices. But this is not so. They were saved by faith alone. “For what does the Scripture say? ‘Abraham believed God, and it was credited to him as righteousness’” (Romans 4:3). “For by it [faith] the men of old gained approval” (Hebrews 11:2).
We are saved by grace through faith in God: specifically in the Messiah. The Hebrew word Messiah (or Christ in Greek) means the “anointed one.” God promised to send a Redeemer, a descendant of Eve, back in Genesis (Genesis 3:15). Only this Messiah can save anyone. The only difference between Old Testament believers and New Testament believers is one of perspective. Old Testament saints looked forward to the coming of the Messiah; New Testament believers look back to what the Messiah accomplished on the cross. But no one comes to God except by Christ (John 14:6).
This is the Gospel: that all who repent and trust in Christ, confessing Him as Lord and believing that God raised Him from the dead, shall be saved. Believers who trust in Christ will not experience the wrath of God, but will instead enjoy His grace and mercy forever in the eternal state. Those who are trusting in someone or something other than Christ shall not enter the Kingdom of Heaven (John 14:6).
Jesus can pay for our sins because He is both God and man. As a man, Christ is our “brother” (Hebrews 2:11-12) and can represent us on the cross. As God, the sinless Christ can pay an infinite penalty since His life is of infinite value (Hebrews 7:26-28). 2 Corinthians 5:21 states of Christ, “He made Him who knew no sin to be sin on our behalf, so that we might become the righteousness of God in Him.” This is called double imputation. That is, our sin is imputed to Christ and He pays for it, whereas His righteousness is imputed to us and therefore God treats us as if we had lived righteously.
Double imputation was symbolized by animal sacrifice in the Old Testament administration. The Israelites would select an animal without any blemishes – this symbolized sinlessness. Then that animal would be killed and burned in place of the person who had actually sinned (e.g. Leviticus 4:22-24). The innocent animal died in place of the guilty person, whereas the guilty person lived in place of the animal. This action did not actually pay for sins since animals are not related to us (Leviticus 25:49). Rather, it served as a reminder of sins and foreshadowed how Christ would actually pay for our sins (Hebrews 10:1-4).
Salvation by God’s grace through faith in Christ is the only way to be reconciled to God. Any alternative promises of salvation are false. The Bible warns that anyone preaching a false Gospel is cursed (Galatians 1:8-9).
5. Repentance from Sin
Jesus commanded people to repent and believe the Gospel (Mark 1:15). That is because repentance of sin and saving faith in Christ always go together. To repent is to change one’s mind, heart, and direction. In terms of the Gospel, repentance means that a person renounces and turns from the sin in his or her life and resolves to walk in obedience to God’s law. 2 Corinthians 7:10 states, “For the sorrow that is according to the will of God produces a repentance without regret, leading to salvation, but the sorrow of the world produces death.” Repentance of sin and salvation go hand-in-hand.
Jesus said, “Unless you repent, you will all likewise perish” (Luke 13:5). It follows then that a person who does not repent of sin and who has no desire to obey God’s law is not saved. He may profess to be a Christian. He may even have a type of faith in Christ and the Resurrection. But the Bible explains that not all faith in God is saving faith. James 2:19 states that even the demons believe in God – that is a type of faith. Yet, their faith does not save them because they have no desire to obey God.
A person who professes Christ but who has no desire to turn away from sin is not saved. “If we say that we have fellowship with Him and yet walk in the darkness, we lie and do not practice the truth” (1 John 1:6). “By this we know that we have come to know Him, if we keep His commandments. The one who says, ‘I have come to know Him,’ and does not keep His commandments, is a liar, and the truth is not in him” (1 John 2:3-4). This verse utterly destroys the claim that we can be right with God, while ignoring His commandments and living like the devil.
Those who teach that we are under no obligation to obey God’s laws as long as we believe in Jesus or pray a sinner’s prayer are teaching a false Gospel. “The one who practices sin is of the devil; for the devil has sinned from the beginning. The Son of God appeared for this purpose, to destroy the works of the devil. No one who is born of God practices sin, because His seed abides in him; and he cannot sin, because he is born of God” (1 John 3:8-9).
This last passage may be difficult – that the one born of God “cannot sin.” Does this mean that genuine Christians lead sinless lives after salvation? Clearly not. Rather, genuine Christians do not practice sin in the sense of freely, willfully, and repeatedly rebelling against God’s law. Christians have a sincere desire to obey God’s law. When Christians sin, they are sorrowful and ask the Lord for forgiveness and for help to live obediently to Him.
Therefore, genuine salvation in Christ is always accompanied by repentance from sin and a sincere desire to obey God’s Word. Fortunately, our salvation is not dependent upon our continued obedience; we are not made perfect in practice at the moment of salvation. However, a faith that saves is a faith that will (eventually) produce visible change in the person. A saved person will be characterized by obedience to God’s Law. That obedience will not be perfect in this fallen world. But good works always follow from genuine faith. A faith that never results in good works is a “dead” faith that does not accompany salvation. This difference between a genuine saving faith that produces good works and a dead faith that does not is explained in James 2:14-26. James rhetorically asks, “What use is it, my brethren, if someone says he has faith but he has no works? Can that faith save him?” The implied answer is: no. A faith that produces no good works is not a saving faith.
Since saving faith and good works go together, people have a tendency to think that good works lead to, or are required for, salvation. That is heresy because it denies salvation by grace through faith in Christ alone. The error is due to fallacious reasoning: the fallacy of false cause. In this case, the error is in reversing the cause and effect. Good works never cause or lead to salvation (Ephesians 2:8-9). Rather, saving faith is the cause that inevitably results in good works. Those who are saved will naturally desire to obey and please God out of love and gratitude for that salvation. Obedience to God’s law is but the lifestyle of faith. Obedience doesn’t save you; rather, obedience is a way of saying to the world, “The Lord saved me!”
So, there is a connection between salvation and good deeds. The former is the cause of the latter – not the reverse. No acts of obedience are required on the part of the sinner for salvation.
Some might say, “But isn’t repenting of sin a work? And isn’t confessing Christ as Lord something the person does?” But in fact, repentance is something that God grants to the person (Acts 5:31, 11:18; 2 Timothy 2:25). Remember that repentance involves a change of heart. And God alone can change a sinner’s heart (Ezekiel 36:26). Also, our ability to confess that Christ is Lord is not something for which we can take credit. It is granted to us by the Holy Spirit (1 Corinthians 12:3).
Anyone who teaches that you must do something in addition to the biblical criteria of “repent and believe the Gospel” (Mark 1:15) in order to be saved is teaching a false gospel. As one example, there are some who teach a form of “baptismal regeneration” in which water baptism is said to be required for salvation/regeneration. But such a claim is contrary to the clear teaching of Scripture as we have seen above. God regenerates a person’s heart; water doesn’t (Ezekiel 11:19, 36:26). Baptism is an appropriate act of obedience out of gratitude for salvation: it’s a way of saying to the world, “I have been saved.” It is an act of obedience; but it is not required for salvation. The thief on the cross was granted saving faith in Christ; he was not baptized in water, yet he entered heaven (Luke 23:39-43).
Saving faith and repentance of sin are both gifts from God (Hebrews 12:2; Acts 11:18; 2 Timothy 2:25). And they characterize a saved person. We know this again from passages such as 1 John 2:3-4 which says, “By this we know that we have come to know Him, if we keep His commandments. The one who says, ‘I have come to know Him,’ and does not keep His commandments, is a liar, and the truth is not in him.”
The True Gospel
The above doctrines are essential because they are the core of the Gospel. The true Gospel saves; a false gospel does not. And we have seen that the Bible explicitly teaches the above doctrines as necessary for salvation – that anyone who denies them is unsaved and walking in darkness. Thus, every local church should embrace and proclaim these core biblical teachings. A church that denies one or more of these core principles is actually a cult, and is teaching a false gospel (Galatians 1:8-9).
Yet, there is another way in which a person can deny the Gospel, while appearing to affirm it. It is possible to verbally profess all the above biblical principles, and still fall short of saving faith. Cults, in particular, often use Christian words and phrases, but endow them with non-biblical meanings. It’s not the words that provide salvation, but God’s grace through faith in Christ. More to come.
 The position that “water baptism is required for salvation” is generally based on two errors: one of exegesis and one of reasoning. The exegetical error is in assuming that ‘baptism’ in the relevant passages must always refer to water baptism. But the Scriptures teach of another kind of baptism (Mark 1:8; Romans 6:3; Galatians 3:27). The logical error is in assuming that since “repent and be baptized” results in salvation, that both are necessary for salvation (e.g. Mark 16:16). As an example, “whatever has feathers and flies is a bird” is a true statement. If someone says, “Ostriches have feathers, but they do not fly. Therefore, ostriches are not birds,” then that person has made the same error in reasoning.
 Some denominations believe that baptism is a way of indicating that a person is part of God’s covenant people – much like circumcision in the Old Testament. Either way, baptism does not cause or lead to salvation.