Denial of Christ is the Spirit of Antichrist
Source: TTT
1 John 2:22, 23
Who is the liar, if it is not the one who denies that Jesus is the Christ? This is the antichrist, who denies the Father and the Son. / Whoever denies the Son does not have the Father, but whoever confesses the Son has the Father as well.
1 John 4:3
and every spirit that does not confess Jesus is not from God. This is the spirit of the antichrist, which you have heard is coming and which is already in the world at this time.