1 John 2:18-19

18Little children, it is [the] last hour, and, according as ye have heard that antichrist comes, even now there have come many antichrists, whence we know that it is [the] last hour.

19They went out from among us, but they were not of us; for if they had been of us, they would have surely remained with us, but that they might be made manifest that none are of us.