The Seriousness of Heresy

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To call someone a heretic is to bring a very serious charge against them. The word is often thrown around amongst Christian groups seemingly without an understanding as to what they are actually saying about someone when they call them a “heretic.”

What is a heretic?

The English word “heresy” comes from the Greek word αἵρεσις (hairesis) and is generally used to refer to someone who deviates from an established religious dogma, or an accepted theory, belief, or practice. The Greek word however originally referred to taking something, choosing something, or even effort directed towards a goal. Eventually the usage of the word evolved and became used to refer to sects, parties, or divisions. For the purposes of this post I will be discussing the term as it relates to Christianity and Christian beliefs and theology. However, the word can also be used outside of this context.

Before moving on I think it is important to note the original meaning(s) of this word as I think they are useful for understanding what heresy is. On a practical level heresy is essentially picking and choosing which doctrines to follow. It is saying, “I like some of what Jesus and the Apostles taught, but not all of it, so I am just going to adhere to the ones I like and discard the rest.” This is essentially what Arius did and why he was ultimately condemned as a heretic. It is important to note also that this is not the same as having questions or doubts about a certain doctrine. It is understanding a doctrine and rejecting it.

Now, as previously mentioned, eventually hairesis became used to refer to sects, parties, or divisions. We can actually see this usage in certain parts of the New Testament:

  • The Sadducees in Acts 5.17
  • The Pharisees in Acts 15.5, 26.5
  • Christians in Acts 24.14, 28.22

It is important to understand that Christians were designated a hairesis by other groups. Christians did not refer themselves as hairesis, but rather as ἐκκλησία (ekklēsia). The word ekklēsia refers to an assembly, gathering, or community. It connotes unity, orderliness, commonality of purpose. It fosters a “we” mentality. A legislative body, for example, could be referred to as an ekklēsia because when it gathers it does so in order to discuss how best to govern a nation. It is opposed to hairesis, which connotes division, strife, and disorderliness. Hairesis fosters an “us vs them” mentality. If we continue with the legislative body example a hairesis would be a group of people within that legislative body seeking to impose their will over everyone else without regard as to the negative effects their policies or ideas might have on the nation.

The church is an ekklēsia because it (ideally) is working together for the good of everyone. Like, perhaps, the various parts of the body work together for the good of every other part of the body. If only the New Testament used such imagery to describe the church…

In any case, in Christian thought hairesis has, from the beginning, referred to a person or group that was outside the Christian community. The uses of the word in Acts, which was written by Luke, who was a Christian, to refer to the Sadducees and Pharisees are an example of this usage. Not only were these groups outside the Christian community, but they were also actively opposed to the message of Christianity and actively worked against it and persecuted Christians.

Hairesis is much more serious than σχίσμα (schisma), which basically refers to splits within a community over differing goals (e.g. John 7.43, 9.16, 10.19-21). A schism could eventually lead to heresy, but a schism itself does not necessarily mean that one group or person has become a heretic. There are few places in the New Testament that show just how serious hairesis is:

  • In 1 Corinthians 11.19 Paul says that there must be hairesis (factions) among the Corinthians so that those are true in their Christian belief might be revealed and recognized as such. So, if you are part of this heretical group your faith is not true.

  • In Galatians 5.20 it is included in a list of “works of the flesh” which if someone does regularly and does not repent of they will not inherit the kingdom of God.

  • In 2 Peter 2.1 it says that those who introduce hairesis will bring destruction upon themselves.

  • In Titus 3.10-11 Paul instructs Titus that a person who is prone to hairesis (αἱρετικὸν ἄνθρωπον) is to be rebuked once or twice and then Titus is to have nothing to do with them because they are “warped,” “sinful,” and “self-condemned.”

There is then, I think, an eschatological dimension to hairesis. Meaning, that it involves ones final eternal destiny to either heaven or hell. A difference of opinion is not hairesis. If you think premillennialism is the “correct” view on the end times that does not mean that people who hold to amillennial or postmillennial views are heretics. It just means they disagree with you. Denying an essential doctrine of the Christian faith is what constitutes hairesis. So, denying the 2nd coming of Christ would constitute hairesis, which by the way all the aforementioned eschatological views hold. Denying any of the doctrines in the Theological Foundations series would (probably) constitute hairesis.


To call someone a heretic is a very serious charge. It is tantamount to saying that they believe damnable doctrine and will spend eternity in hell away from God because of their beliefs. Most of what Christians think is hairesis is actually a difference in opinion on non-essential matters. Perhaps the reason that such accusations are thrown around a lot in American Christianity is because Protestantism, the dominant expression in America basically threw off the authority of the Roman Catholic Church, but didn’t replace it with anything. That is, they basically said, “The Roman Catholic Church is wrong! We don’t know what’s right, but we know that they are wrong!” As a consequence then protestants spend a lot of time arguing over what is right, probably much more than they should.

In any case, please do not accuse someone of heresy lightly. Be absolutely sure that whatever they believe is so bad that it qualifies as damnable doctrine that will lead them to an eternity in hell apart from God.

Addendum: What is heterodoxy?

Heterodoxy is basically somewhere in between orthodoxy and heresy. A heterodox belief is a belief that is not quite right (orthodox), but neither is it exactly wrong (heresy). It is somewhere in between. A heterodox belief will not necessarily lead to a heretical belief. It is just somewhere in between orthodoxy and heresy. If you are unsure of where the beliefs of a certain person or group lie in relation to orthodox belief it is best, I think, to place them in this category until you are more sure of where exactly their beliefs fall.

Photo by Josh Withers on Unsplash

Tom Ferguson ThM 2018, Dallas Theological Seminary