This term in Greek (a·po·sta·siʹa) comes from the verb a·phiʹste·mi, literally meaning “stand away from.” The noun has the sense of “desertion, abandonment or rebellion.” (Ac 21:21, ftn) In classical Greek the noun was used to refer to political defection, and the verb is evidently employed in this sense at Acts 5:37, concerning Judas the Galilean who “drew off” (a·peʹste·se, form of a·phiʹste·mi) followers. The Greek Septuagint uses the verb at Genesis 14:4 with reference to such a rebellion. However, in the Christian Greek Scriptures the noun is used with regard to religious defection; a withdrawal or abandonment of the true cause, worship, and service of God, and hence an abandonment of what one has previously professed and a total desertion of principles or faith. The religious leaders of Jerusalem charged Paul with such an apostasy against the Mosaic Law.

It may properly be said that God’s Adversary was the first apostate, as is indicated by the name Satan. He caused the first human pair to apostatize. (Ge 3:1-15; Joh 8:44) Following the Flood, there was a rebellion against the words of the God of Noah. (Ge 11:1-9) Job later found it necessary to defend himself against the charge of apostasy on the part of his three supposed comforters. (Job 8:13; 15:34; 20:5) In his defense Job showed that God grants no audience to the apostate (Job 13:16), and he also showed the hopeless state of one cut off in apostasy. (Job 27:8; compare also Elihu’s statement at 34:30; 36:13.) In these cases the Hebrew noun cha·nephʹ is used, meaning “[one] alienated from God,” that is, an apostate. The related verb cha·nephʹ means “be inclined away from the right relation to God,” or “pollute, lead to apostasy.”​—Lexicon in Veteris Testamenti Libros, by L. Koehler and W. Baumgartner, Leiden, 1958, p. 317.

Apostasy in Israel. The first two commandments of the Law condemned all apostasy. (Ex 20:3-6) And before Israel’s entry into the Promised Land, they were warned against the grave danger of apostasy resulting from marriages with the people of the land. (De 7:3, 4) Even though a person who was inciting others to apostasy was a close relative or a marriage mate, he was to be put to death for having “spoken of revolt against Jehovah your God.” (De 13:1-15) The tribes of Reuben, Gad, and Manasseh were quick to exonerate themselves of a charge of apostasy that arose because of their construction of an altar.​—Jos 22:21-29.

 Many of the kings of Israel and of Judah followed an apostate course​—for example, Saul (1Sa 15:11; 28:6, 7), Jeroboam (1Ki 12:28-32), Ahab (1Ki 16:30-33), Ahaziah (1Ki 22:51-53), Jehoram (2Ch 21:6-15), Ahaz (2Ch 28:1-4), and Amon (2Ch 33:22, 23). In due time a nation of apostates developed because the people listened to apostate priests and prophets (Jer 23:11, 15) and other unprincipled men who, by smooth words and false sayings, led them into loose conduct, immorality, and desertion of Jehovah, “the source of living water.” (Isa 10:6; 32:6, 7; Jer 3:1; 17:13) According to Isaiah 24:5, the very land became “polluted [cha·nephahʹ] under its inhabitants, for they have bypassed the laws, changed the regulation, broken the indefinitely lasting covenant.” No mercy was to be granted them in the predicted destruction.​—Isa 9:17; 33:11-14; Zep 1:4-6.

What characteristics identify apostates as distinct from true Christians?

An apostasy among professed Christians was foretold by the apostle Paul at 2 Thessalonians 2:3. He specifically mentioned certain apostates, such as Hymenaeus, Alexander, and Philetus. (1Ti 1:19, 20; 2Ti 2:16-19) Among the varied causes of apostasy set forth in apostolic warnings were: lack of faith (Heb 3:12), lack of endurance in the face of persecution (Heb 10:32-39), abandonment of right moral standards (2Pe 2:15-22), the heeding of the “counterfeit words” of false teachers and “misleading inspired utterances” (2Pe 2:1-3; 1Ti 4:1-3; 2Ti 2:16-19; compare Pr 11:9), and trying “to be declared righteous by means of law” (Ga 5:2-4). While still making profession of faith in God’s Word, apostates may forsake his service by treating lightly the preaching and teaching work that he assigned to followers of Jesus Christ. (Lu 6:46; Mt 24:14; 28:19, 20) They may also claim to serve God but reject his representatives, the visible part of his organization. (Jude 8, 11; Nu 16:19-21) Apostates often seek to make others their followers. (Ac 20:30; 2Pe 2:1, 3) Such ones willfully abandoning the Christian congregation thereby become part of the “antichrist.” (1Jo 2:18, 19) As with the apostate Israelites, destruction is likewise foretold for apostates from the Christian congregation.​—2Pe 2:1; Heb 6:4-8; see ASSOCIATION.

During the period of persecution that the early Christian congregation experienced at the hands of the Roman Empire, professed Christians were at times induced to deny their Christian discipleship, and those who did so were required to signify their apostasy by making an incense offering before some pagan god or by openly blaspheming the name of Christ.

It is evident that there is a distinction between a ‘falling’ due to weakness and the ‘falling away’ that constitutes apostasy. The latter implies a definite and willful withdrawal from the path of righteousness. (1Jo 3:4-8; 5:16, 17) Whatever its apparent basis, whether intellectual, moral, or spiritual, it constitutes a rebellion against God and a rejection of his Word of truth.​—2Th 2:3, 4; see MAN OF LAWLESSNESS.