The word apostasy is derived from a Greek word meaning “revolt,” and has come to mean specifically, according to the Merriam-Webster online dictionary, “abandonment of a previous loyalty” and “renunciation of a religious faith.”
Readers of some New King James Version Bibles will notice that, although this word does not appear in the text of the Bible itself, the editors used the word in the headings of several sections of Scripture. These five sections (beginning in 2 Chronicles 24:15 2 Chronicles 24:15But Jehoiada waxed old, and was full of days when he died; an hundred and thirty years old was he when he died.
American King James Version×; 2 Chronicles 28:22 2 Chronicles 28:22And in the time of his distress did he trespass yet more against the LORD: this is that king Ahaz.
American King James Version×; Hosea 8:1 Hosea 8:1Set the trumpet to your mouth. He shall come as an eagle against the house of the LORD, because they have transgressed my covenant, and trespassed against my law.
American King James Version×; 2 Thessalonians 2:1 2 Thessalonians 2:1Now we beseech you, brothers, by the coming of our Lord Jesus Christ, and by our gathering together to him,
American King James Version×; and 1 Timothy 4:1 1 Timothy 4:1Now the Spirit speaks expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils;
American King James Version×) each address a “falling away” from God by an individual or a group.
The first three deal with two kings and a nation that turned their backs on God. Each is worth studying to understand the dangers of apostasy from God and what can bring it about. But even more pertinent are the last two references, both of which are titled “The Great Apostasy” in some New King James Version Bibles.
What these two scriptures describe is a time coming in the future, the “falling away” (2 Thessalonians 2:3 2 Thessalonians 2:3Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition;
American King James Version×), when “some will depart from the faith, giving heed to deceiving spirits and doctrines of demons, speaking lies in hypocrisy” (1 Timothy 4:1-2 1 Timothy 4:1-2  Now the Spirit speaks expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils;  Speaking lies in hypocrisy; having their conscience seared with a hot iron;
American King James Version×). The event is explained as a precursor to the coming of God’s Kingdom (2 Thessalonians 2:2-3 2 Thessalonians 2:2-3  That you be not soon shaken in mind, or be troubled, neither by spirit, nor by word, nor by letter as from us, as that the day of Christ is at hand.  Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition;
American King James Version×) and something that believing Christians must be on guard against.
To be on guard against apostasy, we must be keenly aware of who God is and what He commands—a state that must be maintained by continuous Bible study and prayer. Below are some resources to help you sharpen your spiritual sword.
Please read our free Bible study aid booklet Transforming Your Life, the Process of Conversion.