***The term does not appear in the Bible save for the Epistles, so no other Apostle, who actually knew Christ in Person, taught it or knew it for that matter.***
Direct quote from you. You said no other apostle taught it or even knew about it. You are wrong. Someone other that Paul did teach it and so, obviously knew it. Was 1st Peter written by Paul? No. Was 1st Peter written by ... um... Peter? Was Peter an apostle? As an apostle, then, when he wrote about sanctification, did he or did he not know what he was writing about?
Ummm. No! Peter was written long after Peter was dead.