“Churches that have had their lampstand removed are apostate. Churches that are being seriously warned about that possibility are corrupt. Branches that have been cut out of the olive tree are apostate. Branches that are still on the tree but have started to think that they support the root are corrupt. The short answer is that apostasy does not occur with no warning at all—the run up to that apostasy is the period of corruption. God dealt with the Israelites even though they worshipped him in the high places. They were corrupt, but not yet rejected. The prophets were ticked about it, as they should have been, but God nevertheless still owned them as His people. That was corruption, not apostasy. The severance of Israel from the olive tree after 70 AD was apostasy, the culmination of corruption.
The Auburn Avenue Chronicles Vol. 2, p. 510.