Now, what about going back to unbelief, like the Galatians did.This is the issue that does not get addressed well. Everyone gets hung up on works.
What happened with the Galatians was a kind of syncretism, adding the Law and its observances to the Gospel, which in effect if embraced would have nullified Christ’s work. Very serious. Paul dealt with it, and there is no reason not to believe that those who knew God heeded and responded rightly to Paul’s warning, admonition, and instruction.
How do we know? Because John wrote “whoever is of God hears us (apostles), so it follows that whoever does not hear when it comes to apostolic authority and essential salvation issues, is not of God.
Those who were of God would have received Paul’s words, just as those who are of God today receive them, (and all of scripture as well) not as words of man, but as they are in truth, the very words of GOD