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.
but they went out, that they might be made manifest that they were not all of us: These false teachers separated themselves from the faithful ones that it might be clearly seen that they really did not belong to Christ. "Not all of us" literally means, "None of them had their source in us." Had they remained among the disciples, they would have communicated a false impression of Christianity to the world. It was good for the church there and those whom the church influences that these Christ-opposers had gone.