Insist on the Incarnation

1 John 2:21-25 I write to you, not because you do not know the truth, but because you know it, and because no lie is of the truth. Who is the liar but he who denies that Jesus is the Christ? This is the antichrist, he who denies the Father and the Son. No one who denies the Son has the Father. Whoever confesses the Son has the Father also. Let what you heard from the beginning abide in you. If what you heard from the beginning abides in you, then you too will abide in the Son and in the Father. And this is the promise that he made to us—eternal life. 
As John seeks to encourage these believers over the exodus of some people from the church, he reminds them that they have believed the truth about Christ - He is the incarnate Son of God. The incarnation is absolutely essential to salvation.  If we don't have that, we don't have eternal life. Without the Eternal Son entering human history redemption does not happen.  We need to stand firmly upon that conviction, then we can walk confidently in this life and into the life to come.