Jesus is the truth

Religions such as Islam, or even Jehovah's Witnesses, deny that Jesus was God incarnate, and that He fulfilled the Messianic role of Saviour. But if you take Jesus out of Christianity, then there is no Christianity. To deny Christ - to be an anti-christ - is to deny the way, the truth and the life. And so John encourages his readers to remain faithful to the truth, that is, Jesus!