They went out from us, but they didn't belong to us; for if they had belonged to us, they would have continued with us. But they left, that they might be revealed that none of them belong to us.
"If you will investigate the history of the false cults and antichristian religious systems in today’s world, you will find that in most cases their founders started out in a local church! They were ’with us’ but not ’of us,’ so they went out ’from us’ and started their own groups." [Note: Wiersbe, p. 499.] 