They went out from us, but they did not really belong to us. In other words, antinomians are antichrists. These were antinomian leaders, antinomian teachers, and they were kicked out. They were disciplined. They were sent out from the church of Jesus Christ in order that the church be kept pure.
Antinomianism is a heresy.
Peter says the same thing in 2 Peter. 2 Peter, like Jude, was written to combat this heresy of antinomianism. This was the essence of their teaching. No wonder American churches, especially those of evangelical persuasion, are filled with people. Everybody likes that, you see.