American Standard Version (ASV):
They went out from us, but they were not of us; for if they had been of us, they would have continued with us: but [they went out], that they might be made manifest that they all are not of us.
King James Version (KJV):
They went out from us, but they were not of us; for if they had been of us, they would [no doubt] have continued with us: but [they went out], that they might be made manifest that they were not all of us.