Expositor's Bible Commentary Commentary 1 John 2:19

"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." — 1 John 2:19 (ASV)

The departure of the opponents may have had a greater effect on the congregation than the reason for it. The early church obviously had severe debates, with significant differences of opinion being expressed. Yet as far as we know, no one thought that “separation from the congregation” was an option for anyone professing faith in Jesus. Departure, like Judas’s going out from the community of disciples, pointed to betrayal, denial of faith, and separation from God’s grace. That is why John acknowledges that those false teachers, whom he now designates as antichrists, had been regular members of the congregation. “They went out from us,” he says, but hastens to add, “they did not really belong to us.” Like Judas, they had been nominal members of the community and had never truly shared its fellowship.

John goes on to teach the significance and abiding nature of life in the community. “If they had belonged to us, they would have remained with us.” Those who have actually been a part of the divine life will without fail persevere in the community. But in order that the true nature of the false teachers might be exposed, “they went out from us,” so that the community might know that “none of them belonged to us” (cf. Matthew 24:24).

Expulsion from the Christian community for misdeeds was and is a serious act, and hopefully it lasts only long enough to allow for repentance and restoration (cf. 1 Corinthians 5:2–5; 2 Corinthians 2:5–11). The case at hand is unique; the departure of the opponents was not expulsion or excommunication but a voluntary departure. It shows that they were never truly members of the community.