‘For many deceivers are gone forth into the world, even those who do not confess that Jesus Christ comes in the flesh. This is the deceiver and the antichrist.'
Mention is now made of those whom they should guard against, the deceivers, those who deny that Jesus the Christ came in the flesh as a human being. These are the deceivers and the antichrist (1 John 2:18-21). They set up someone else as the Christ in the place of Jesus, a Christ who did not come as true human and die on the cross, and thereby they seek to deceive true believers. In our day this is partly true of Islam, who reduce Jesus, even though they call Him Messiah, and deny His death. And they may well prove to produce the final Antichrist. And one of the ways by which they are known is that they do not love the Son, do not love the truth as it is in Jesus, do not love His commandments, and do not love His true people.
Note that these deceivers have gone forth into ‘the world' in contrast with the church. They have withdrawn from the true fellowship of the people of God. ‘They went out from us because they were not of us' (1 John 2:19).