1 John 2:18-19

Dear children, the end of this age is near! You have heard that Antichrist is arising, and in fact, many enemies of Christ have already appeared, and this is how we know that we are living in the closing hour of this age. For even though they were once a part of us, they withdrew from us because they were never really of our number. For if they had truly belonged to us they would have continued with us. By leaving our community of believers they made it obvious that they never really belonged to us.