“…I praise ye not, … I hear that there be schisms among you, … For there must be also heresies among you, that the approved might become manifest among you.” (1 Cor. 11:17-19)
“They went out from among us, but they were not of us; for if they were of us, they would have remained with us; but that they might be made manifest that they are all not of us.” (1 Jn. 2:19)