What is "Apostasy"?

What does it mean to "apostatize"? How does one become an "apostate"? What does it mean to "fall from grace"? (Galatians 5: 4)

If a believer commit any sin, from the least to the greatest, is he then immediately an "apostate" and severed from Christ and salvation? Is it only certain grievous sins that sever one from Christ and salvation?

Or, is "apostasy" and "falling away" restricted to certain specific kinds of sins?

I believe that the "falling away" most often addressed by the New Testament writers refers to what we call the "renouncing" of Christ and the gospel, the rejection of the Christian religion which was formerly "professed," or "confessed," or "believed."

"Falling away" is not a phrase or word that is used for every instance where a Christian sins. If it did, then "falling away," or to commit "apostasy," would be a daily common occurrence with all believers, and not that which takes place only occasionally and with only some professing believers.

A Christian sins, including even the holy apostles. The writer to the Hebrews spoke of "the sin that does so easily beset us." (Hebrews 12: 1) Does "apostasy" from Christ "beset" Christians as easily as sin "besets" us? It would if a Christian became an "apostate" every time he committed transgression.

More to come.