What does 1 John 2:19 mean?

John further describes the traits of "antichrists" as those who "went out from us, but they were not of us." These false teachers claimed to be believers, but were not. John explains why: "if they had been of us, they would have continued with us." John uses the idea of "continuing" to refer to ongoing or repeated action. Those who did not last in the faith, particularly those who claimed to be leaders in the church, but turned against God, were literally against Christ or antichrists.

John adds, "But they went out, that it might become plain that they all are not of us." This abandonment of the faith offered proof or evidence that these false teachers were not true believers (1 John 2:22–23). In contrast with those who had been anointed (1 John 2:20), these false teachers did not have God's Spirit within them. They did not know the truth (1 John 2:21), denied Jesus is the Christ (1 John 2:22), and deceived others (1 John 2:26).