In Greek it means as a verb to ‘stand away from’. As a noun ‘abandonment, rebellion’. To defect from true worship. To reject God and His Son.

The specific Greek noun apostasia (ἀποστασία), meaning “rebellion,” “abandonment,” or “falling away”, appears twice in the Greek New Testament: Acts 21:21 and 2 Thessalonians 2:3. It refers to a departure or defection from the true faith.

Definition: Derived from apo (away from) and histemi (to stand), it refers to a standing away from, or abandoning, a previous position.

Verb Form: The related verb aphistēmi (to depart or fall away) is used more frequently (e.g., Luke 8:13, 1 Timothy 4:1).

Acts 21:21: Used in the context of Paul being accused of teaching Jews to “forsake” (apostasia) the law of Moses.

2 Thessalonians 2:3: Predicts a “falling away” (apostasia) or rebellion that must occur before the day of the Lord.

The word “heresy” in the Greek New Testament is a translation of the Koine Greek word hairesis (αἵρεσις). While modern English defines heresy as false doctrine, the Greek word originally meant “a choosing,” “choice,” or “party,” frequently used to describe sects or factions, such as the such as the sect (hairesis) of the Sadducees, Pharisees, or Nazarenes (Acts 5:17, 15:5, 24:5).

Key Details on Hairesis in the New Testament:

Original Meaning: Hairesis (Strong’s #139) refers to a choosing or a sect/school of thought.

Neutral Usage: It is used neutrally to describe groups, such as the sect (hairesis) of the Sadducees, Pharisees, or Nazarenes (Acts 5:17, 15:5, 24:5).

Negative Usage: It is used negatively, translated as “factions,” “sects,” or “divisions” when referring to self-willed opinions that destroy church unity (1 Cor 11:19, Gal 5:20).

Doctrinal Context: 2 Peter 2:1 specifically warns of “destructive heresies” (hairesis) brought in by false teachers.

Development: By the early second century, the term shifted from merely meaning a “sect” to a “departure from orthodoxy”.

In short, the Greek word is present, but it primarily refers to divisive factions or sects rather than the modern definition of strictly false doctrine, though the latter is implied in its usage regarding church divisions. 

I’ll give you a number, but I’ll also be very clear about what that number does and does not mean, because historians don’t usually speak this way.

Short answer (with a percentage)

For a religion with early written sources, multiple independent communities, public debate, and hostile critics:

≈ 5–10% likelihood that it has fundamentally misunderstood or inverted its core beliefs by ~120 years after the originating events.

And even that is probably generous.

Why that number is low

This estimate is based on how belief transmission actually behaves in history, not on theology.

By 120 years, in cases like early Christianity, you typically already have:

• Primary texts written within living memory of eyewitnesses
• Copies spread across regions (not centrally controlled)
• Internal disagreements recorded in writing
• External critics who quote and attack the beliefs
• Martyrdom tied to specific confessions
• Liturgical practices reflecting belief (worship, prayer)

Under those conditions, total misunderstanding of core claims is very unlikely.

Historians know that:

• Peripheral ideas drift easily
• Terminology evolves
• Philosophical explanations mature

But who is worshipped, what is confessed, and what counts as heresy are extremely resistant to accidental reversal.

What the 5–10% allows for

That small percentage accounts for possibilities like:

• Early but systematic misunderstanding shared by all communities
• Loss of a key interpretive framework very early
• A founder whose message was radically ambiguous
• A movement that mythologized almost immediately

These things can happen—but they leave traces.

And when they happen, we usually see:

• Competing sects preserving older views
• Explicit accusations of corruption
• Fragmentation that never fully resolves

Why the number is not higher

For the likelihood to be, say, 30–50%, we would expect:

• No early texts
• Centralized authority rewriting doctrine
• Suppressed dissent
• Late standardization
• No hostile witnesses

That describes some movements in history.

It does not describe early Christianity by 120 CE.

An important contrast (this sharpens the answer)

A later group (1,500–1,800 years on) reinterpreting the same texts differently, without new evidence

Likelihood of that being correct over everyone before them:

< 1%

Not because people are stupid—but because:

• They are removed from the language environment
• They lack native cultural intuitions
• They rely on selective grammar arguments
• They disagree with every known ancient reader
• They introduce readings no one noticed when Greek was alive

Historians are extremely skeptical of that scenario.

Bottom line

• 120 years after the events:
  → Low but non-zero chance of major error (~5–10%)
• 1,800+ years later, with no new data:
  → Vanishingly small chance (<1%)

If you want, we can tighten this further by:

• Comparing known cases where religions did get core beliefs wrong
• Running the same estimate for Islam, Buddhism, or Mormonism
• Or testing this logic against a specific doctrine you have in mind

You’re asking the right kind of question.

We hear about the great apostasy, mostly from Latter-day Saints, Mormons, Seventh day Adventists, but is there biblical evidence for it?

The presupposition of organisations such as those mentioned above is it ocurred in the past.

We want to be open to what the evidence has to say, and that includes when such an event might occur, if there’s a basis for it.

There have been multiple other groups that have claimed that there was a great apostasy, Mormons or the Watchtower did not originate the idea. It actually originated at least in a way that affected entire movements in Protestant circles, and of course Mormonism is an outgrowth of Protestant circles, you know, with additional reported revelation through Joseph Smith and so forth.

As it’s commonly articulated, the idea of the great apostasy is that something went really, really badly wrong in the early Church, either in the first century or the first few centuries, and basically anybody who’s part of a non-historic Church, one that arose only recently, say since the time of the Reformation, is potentially open to this idea that something went really wrong in the early Church that they could then refer to as a great apostasy.

The idea was more common in mainstream Protestant circles back during the 1500s and the 1600s, but it has retreated in mainstream Protestant circles, but it is still found in some places. Those include among Seventh-day Adventists, Mormons, Jehovah’s Witnesses, and hyper-dispensationalists.

So it’s found among a range of different groups that are basically outgrowths in one way or another of Protestantism. But if we set aside the timing of the theory as it’s commonly been expressed by these groups, and just say, is there a basis for something that you could call a great apostasy in Scripture? Well, the answer is yes.

There is a passage, and this is one that is commonly appealed to by these groups, that discusses something that you could call a great apostasy, and this passage is in 2 Thessalonians 2, where Paul is writing, and he says, “now concerning the coming of our Lord Jesus Christ, and our being gathered together to him”.

And that is a reference to something that Paul had taken up in his first letter to the Thessalonians. In 1 Thessalonians 4, he was dealing with some confusion that existed in the Thessalonian church, he had only been able to stay with them for a few short weeks before he had to move on. So he didn’t have time to give them a full course of Christian instruction.

So some of them, some of the Thessalonians were now confused about things like, ‘has the day of the Lord come?’ There is a basis for that confusion in 1 Thessalonians.

In 1 Thessalonians 5, Paul talks a fair bit about the coming of the day of the Lord, and in 1 Thessalonians 2, he observes that the Jews, who have rejected Christ, have now had God’s wrath come upon them. And so that, you know, the idea they persecuted Christ, and they persecuted Christians, and they’re hindering Paul’s ministry of preaching the gospel, and now at last wrath has come upon them.

So there had been some kind of setback in the Jewish community. And you can see how if the Thessalonians had the idea that, oh, well, when the day of the Lord happens and Jesus comes back, you know, his enemies are going to be called to account, they’re going to be punished. So Paul replies, “ok, wrath has come upon the Jews”.

So that’s possibly what was causing the confusion. It was very likely a misunderstanding of what he’d written in 1 Thessalonians. But he wants to assure them that they don’t need to worry about that because he says, “let no one deceive you in any way for that day, the day of the coming of our Lord and of our being gathered together with him, that day will not come unless the rebellion comes first”.

And the word for rebellion that he uses in Greek is apostasia. Apostasia is the basis of the English word apostasy. So Paul indicates there is going to be an apostasy that happens before the day of the Lord.

And the question would then be, what’s the nature of that apostasy? Paul gives another sign. He says, not only will that day not come unless the rebellion comes first, and this is the second thing, the man of lawlessness is revealed. The son of destruction who opposes and exalts himself against every so-called God or object of worship, so that he takes his seat in the temple of God, proclaiming himself to be God.

And all this gets into some very interesting territory, but fundamentally, Paul associates the apostasy with the events immediately before the second coming of Christ.

There is another reason that one would not want to interpret the great apostasy as an event occurring early in church history, and that is found in Matthew 16, where Jesus tells Peter, you are Peter, and on this rock I will build my church, and the gates of hell will not prevail against it, or the gates of Hades, to use the Greek word hades, will not prevail against it. Well, the gates of Hades is a reference to the realm of the dead.

The Hebrew equivalent of that is the gates of Sheol, Sheol being the realm of the dead, and when you go to read the Old Testament, either in Hebrew or in Greek, we find references to the realm of the dead being referred to entering the realm of the dead as passing the gates of Hades, or passing the gates of Sheol, and so by saying that the gates of Sheol are not going to prevail against His church, Jesus is saying His church is never going to die, and that means that even though things could and did go wrong in the early church, they couldn’t go so wrong as to cause the church to cease to exist. And that’s presupposed by various understandings of the incorrect great apostasy theory.

Also, in Matthew 28, Jesus tells the disciples, “behold, all authority in heaven and earth has been given to me, and I’m going to be with you until the end of the age”, so Jesus is saying that He is going to be with His church until the end of the world, so we have multiple indications that no matter how bad things go in the world, or even in the church, the church will survive. It’s not going to go out of existence, and Jesus is going to be with it until He comes back at the second coming. When most people talk about ‘has Jesus come back yet?’, they mean the second coming.

There is significant biblical evidence in favour of a great apostasy, but it’s in our future, not in the past.