‘I have not written to you because you do not know the truth, but because you do know it, and because (or ‘that') no lie is of the truth. Who is the liar but he who denies that Jesus is the Christ? This is the antichrist, even he who denies the Father and the Son. Whoever denies the Son, the same does not have the Father. He who confesses the Son has the Father also.'
John immediately assures them that he has not so written because he considers them ignorant of the truth, but because he is well aware that they do know the truth because of the anointing that is in them. He is confident that they can therefore discern lies, that is, false teachings, and recognise their falsehood, not giving place to them for an instant.
He then depicts as liars (men who proclaim the lie - compare 2 Thessalonians 2:9-11; 1 Timothy 4:2; Romans 1:25) those who deny that the man Jesus is the Christ, and indicates that by this that he means those who deny the true Sonship of the Son.
Messiahship (Christhood) had by now among Christians gone far beyond an earthly figure. Jesus had been physically raised and established in Heaven as both ‘Lord and Christ', the highest possible accolade (Acts 2:36). He had been revealed as God's only Son (John 1:14; John 1:18; John 3:16-18 compare Acts 4:27), set at God's right hand, the visible expression of the authority of the invisible God. His uniqueness and essential relationship with the Father was now certain. Thus to deny that Jesus was the Christ indicated denying His true Sonship, and by this denying the Father. God as Father was now directly so linked to His relationship to the Son that there could be no acceptance of the Father without acceptance of the Son. Their inter-relationship was now seen as such that it was both or none. The connection of Father and Son in the way John does here confirms that he sees both as of the same essence. To deny One is to deny the Other.
There is no greater lie than to deny the Christhood and Sonship of Jesus. It strikes at the very root of existence, for He is the basis for our existence and for our hope. It is a lie against all that is.
For the confessing and denying of Jesus compare Matthew 10:32; Luke 12:8; see also John 12:42, but there the thought was of Him being confessed as One sent from God, here it refers to acknowledging His true Sonship. To confess is to declare belief in and to declare loyalty to, to deny is to reject belief in and to refuse loyalty.
‘Whoever denies the Son, the same does not have the Father. He who confesses the Son has the Father also.' The point here is that not to recognise the Son means that such a person does not ‘have the Father', that is does not know Him or experience Him or have Him dwelling within (John 14:23), for if he did he would necessarily fully acknowledge the Son, the title indicating that He was of the same being and essence, because of the Father's witness to Him within. For to the one who is truly a Christian both Son and Father have come to dwell within (John 14:23 compare 2 Corinthians 6:16)