There are plenty of instances where Christians systematically believe something false and directly contradicting biblical teachings, yet they are not deemed to be so errant as to disqualify them from salvation and from fellowship with the universal Church.

By way of example, predestination unto salvation is a mutually exclusive belief about the nature of God such that some Christians directly deny it and others directly confirm it, yet neither believes the other to be heretical.

Yet it is almost universally held in Trinitarian Christianity, that denial of the Trinity is a renunciation of Christianity and salvation.

Why? Why isn't it simply, wrong? Is it mainly due to the early historical discernment of the early councils, or is there a better, biblical argument for this case?

I'm coming from a Protestant perspective. Certainly, a Catholic perspective could get away with saying, "The Church has denounced it." For a Protestant, what does it take before something is properly known as a heresy?

relevant: What is "heresy"?

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    The idea that challenges to Trinitarianism are challenges to the Gospel is not entirely correct. One of the main challengers to Trinitarianism is Sabellianism (a.k.a. Modalism, or sometimes, "Oneness"), which affirms Christ's Deity, that God took on flesh, that Christ was fully God and fully man, along with every other claim about Christ in Scripture. Trinitarianism is just an attempt at explaining many of the explicit claims of Scripture, as is Sabellianism ... but both would affirm the message of the Gospel as found in Scripture.
    – Jas 3.1
    Commented Jan 9, 2013 at 23:55
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    However modalism would have trouble explaining the propitiatory nature of the cross, which is a gospel issue. It also can't say that Jesus is our intercessor.
    – curiousdannii
    Commented Mar 12, 2014 at 6:05
  • "Yet it is almost universally held in Trinitarian Christianity, that denial of the Trinity is a renunciation of Christianity and salvation." Would be interested in polling data on this. Commented May 18, 2022 at 18:59

5 Answers 5


A famous quote from Christian history is:

In Essentials Unity, In Non-Essentials Liberty, In All Things Charity

In Essentials Unity

The Apostle Paul talks about "another gospel" that was being preached to the Galatians, and he uses very strong words regarding those who bring such a gospel:

6 I am amazed that you are so quickly deserting Him who called you by the grace of Christ, for a different gospel; 7 which is really not another; only there are some who are disturbing you and want to distort the gospel of Christ. 8 But even if we, or an angel from heaven, should preach to you a gospel contrary to what we have preached to you, he is to be accursed! 9 As we have said before, so I say again now, if any man is preaching to you a gospel contrary to what you received, he is to be accursed! Galatians 1:6-9 NAS

The concept is that there is one true gospel that leads to eternal life. As Jesus said in Matthew 7, there is one narrow road that leads to life and one wide road that leads to destruction.

So, we only have unity with those who hold to the essentials of true gospel of Jesus Christ. To put it another way, we only have unity among those with whom we will spend eternity. We do not have unity with those who preach another gospel that does not lead to life. We have charity, but not unity.

So, the question becomes centered on what are the essentials. From an evangelical perspective, the essentials typically include the nature of God (including the Trinity) and salvation by grace alone through faith alone in Christ alone. Thus, whatever departs from that is considered heretical.

John's first epistle speaks about the necessity of correct Christology and Theology:

I have not written to you because you do not know the truth, but because you do know it, and because no lie is of the truth. 22 Who is the liar but the one who denies that Jesus is the Christ? This is the antichrist, the one who denies the Father and the Son. 23 Whoever denies the Son does not have the Father; the one who confesses the Son has the Father also. 1 John 2:21-23

Specifically, the "liar" is the one who denies that Jesus is the Christ. The antichrist is the one who denies the Father and the Son. This is understood by many to deny the nature of Jesus as the eternal Second Person of the Trinity.

Additionally, John also writes that anyone who denies Jesus as having come in the flesh is antichrist:

For many deceivers have gone out into the world, those who do not acknowledge Jesus Christ as coming in the flesh. This is the deceiver and the antichrist. 2 John 1:7 NAS

In Non-Essentials Liberty, All Things Charity

We may disagree with others about election or the end times, and there is freedom in that. I personally disagree with my pastor about a few things, primarily, but not limited to eschatology. Yet we still have unity.

I am exhorted to oppose those who hold beliefs I consider heretical, but I do so with charity.

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    I was operating on the premise that believing in a different gospel is essentially the same thing as being a heretic, because it professes to be Christian and yet disqualifies from salvation. My question is, "In what way does denial of the Trinity constitute a different gospel such that other differences (such as predestination) does not constitute a different gospel?" Commented Jan 9, 2013 at 18:44
  • @BenMordecai I added some references to 1 and 2 John.
    – Narnian
    Commented Jan 9, 2013 at 19:21
  • The references are very helpful. So the argument is essentially that denial of the Trinity is in essence what is meant in the cited passages in 1 & 2 John, and therefore this deviation is significant enough to be deemed a different gospel contrary to the one received. Commented Jan 9, 2013 at 20:26
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    @BenMordecai Why not ask that "follow up question" as its own question with a link to this one as a reference. That way it is preserved in a question. Commented Jan 12, 2017 at 20:48
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    Well, the answer is that Trinitarianism did exist from the beginning, it just took time for it to develop a confessional form that was evaluated and received by the church. The Nicaean formulation was only possible because the church did hold to Trinitarian views prior to it. Commented May 19, 2022 at 19:25

Narnian's write up is quite well done, but to try and distill it down a bit, the core issue is criticality of belief. Typically in Christian circles this revolves around salvation and the nature of the Trinity is considered by most to be critical to the nature of salvation.

Effectively, a Christian would believe someone to be a heretic if what they say is so far removed theologically as to be an incompatible belief, whereas they may see someone as simply wrong (that is, incorrect, not morally wrong) if it is in an area seen as non-critical. (For a soft-ball example, most Christian's don't see it as a critical deficiency in someone's theology if they have a different view of the book of Revelation.)


It is "just wrong". It simply means "you are wrong (according to what we accept as Truth) so you can't call yourself (be in communion with) one of us". And yes, believing in predestination of salvation does make you a heretic in the eyes of the Catholic and Orthodox churches.

Protestant traditions are sometimes a little more flexible and forgiving when it comes to differences in belief, but there are certain things (i.e. Trinity, Salvation by Grace, etc) that are so core to Christianity that most* Christians will consider those with contrary beliefs (i.e. Momons) to be heretics, even if they don't use that word.

*for some definition of "most"

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    The Catholic Church affirms predestination. For example, the Council of Trent, Session 6, Chapter 12 says, assuming predestination: "No one, moreover, so long as he is in this mortal life, ought so far to presume as regards the secret mystery of divine predestination, as to determine for certain that he is assuredly in the number of the predestinate; ... for except by special revelation, it cannot be known whom God hath chosen unto Himself." But Session 6 does reject double predestination (i.e. absolute positive reprobation, rather than negative, permissive reprobation) in Canon 6. Commented Sep 9, 2017 at 21:25

For me this boils down to idolatry. If you worship a none-triune God, you have constructed a god that is not the same God as the God of the Bible. So it's heretical rather than just simple doctrinal disagreement because you are not even worshiping the same God. It doesn't matter if you call it god, it's not God. This goes against the first commandment. But more than that I can say this qualifies as blasphemy against the Holy Spirit to say that the Holy Spirit does not exist or is not God. Mark 3:29 states "but whoever blasphemes against the Holy Spirit never has forgiveness, but is guilty of an eternal sin”

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    On a personal level, I agree with you that it is idolatry, but I think an issue with that is that it's an argument that proves too much. Denial of God's Trinitarian nature sets up an idolatrous version of God in it's place, but that could be similarly said about someone who, say, denies that God is sovereign in salvation. The side that is wrong is setting up an idolatrous version of God for worship. How is the distinction made between these types of idolatry? Commented Jan 12, 2013 at 1:52
  • @BenMordecai The difference is one is a disagreement about how God acts, the other is a disagreement of what God is. I don't see any one arguing against pre-destination that denies God has the power to enforce His will, just that He allows free will anyway. And it's as you say, each group doesn't typically label the other heretic on those matters(with exceptions of course). So the distinction on Idolatry is are we disagreeing about God's nature or His choices.
    – 2tim424
    Commented Jan 12, 2013 at 2:06

I would like to point out that it is not common to jump to the conclusion that someone is a heretic flatly because of their lack of understanding of the Trinity, this can be the case and often is; however, more clarification may help in this discussion.

That being said, the Trinity is something that a Saved believer will come to affirm as it is Truth; however - upon being Justified, there is not necessarily outpouring of all understanding bestowed upon the believer per se'.

It is possible to become a sincere Christian, and to then grasp onto more Godly concepts as the Lord works out His plan of Sanctification for the believer. If a newly Born Again adherent is unaware of the Truth of the Trinity at the onset - he is possibly not engaging in active heresy; it may be the case that he or she has not had that aspect of God's Nature revealed to them as of yet. I would contend that this is a rare case, but is certainly possible.

That being said, it is proper for Christians to affirm the Trinity, as it is clearly taught in Scripture.

Many others have done well to make valid points concerning this topic, but I'd like to take the most simple and effective approach to answering. We can go all over the Scriptures and see evidence that the Trinity is a sound and rightful Doctrine, in both the Old and New Testament.

Unfortunately, I do not have the time presently to show in an exhaustive manner all of these evidences here; also I want to address the topic at hand rather than provide all evidence that it is in fact a Truth.

Also, although it can be clearly shown to be a Truth from Scripture, it should be understood that it is not possible for man to fully comprehend it in totality. It is, however, clearly a reality, despite our inability to fully ascertain the inner workings of God's Nature of Being (Trinity).

I will conclude with my answer by demonstrating that it is simply not possible for a Born Again believer to maintain in some ongoing fashion a denial of the Trinity by using Christ's own words:

Matthew 28- The Great Commission

16 But the eleven disciples proceeded to Galilee, to the mountain which Jesus had designated. 17 When they saw Him, they worshiped Him; but some were doubtful. 18 And Jesus came up and spoke to them, saying, “All authority has been given to Me in heaven and on earth. 19 [e]Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit, 20 teaching them to observe all that I commanded you; and lo, I am with you [f]always, even to the end of the age.”

Christ Himself, who is God, not only affirms this aspect of His own Nature of Being, but ties in His direct mention of it with the Great Commission; a foundational command which all true Christians follow.

1) Christ has ALL Authority in Heaven, and on Earth. (We can know He speaks Truth about all matters as He is God Himself, the second person of the Trinity) 2) It should be understood that God would never command His own followers to baptize in any other name than His own.
3) Clearly the Trinity is taught by Christ Himself, therefore, all true Christians - upon this truth being revealed to them will affirm it.

I hope this helps, but a small bit of further clarification may be required, while I explained it may for a time be unclear for a newly Saved believer (simply wrong/uneducated on the Doctrine), ongoing rejection of the Truth of the Trinity would and should be considered Heresy.

  • As a side note I'd like to add that Catholics do in fact affirm the Doctrine of the Trinity.
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    Just to clarify, I'm not really talking about someone who lacks an understanding in the Trinity, generally this would be referring to someone who understands it and yet rejects it. Commented Jan 12, 2013 at 3:18
  • @Ben Mordecai: There are very few that understand it then reject it. Most who reject it simply do not understand it. It's obvious when they start talking about the Trinity.
    – user900
    Commented Jan 12, 2013 at 7:27
  • -> I understand you weren't specifically talking about someone who lacks understanding of the Trinity, but when it comes to the question of Heresy - the distinction needs to be made for general clarification that ongoing denial of such a Truth is fundamentally different than a misunderstanding.
    – Jeremy
    Commented Jan 12, 2013 at 14:01
  • -> Also, in the original question it is made clear the asker is of Protestant mind set, and the asker goes on to make a false statement to demonstrate how a Catholic 'could' deny such a Doctrine by appealing to 'the Church'. I was merely pointing out that this is not a good example being that Catholics do affirm this Doctrine. Also, it is an objectively true statement to mention that Catholicism is rife with apostasy AS SEEN from the Biblical Christian perspective. The person asking claims this is his perspective, therefore it needed to be addressed in my opinion. This is not Catholic bashing.
    – Jeremy
    Commented Jan 12, 2013 at 14:05
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    @H3br3wHamm3r81 actually you might be surprised how many there are. It's not mainstream, but there are entire groups like Oneness Pentecostalism who understand the doctrine of the Trinity and reject it. Commented Jan 12, 2013 at 18:42

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