Deny Son, Deny Father

1 John 2:23 says that whoever denies the Son denies the Father as well, and vice versa – whoever confesses the Son confesses the Father. What’s the logic here? Is John assuming that Jesus is the mediator who makes a way to the Father, so that denying him closes off the way to the Father? Perhaps. But John might also, already, be employing a form of argument later found in Athanasius: If you deny the Son, then you deny that the Father is Father, since a Father must have a Son; if you confess the Son, then you confess the Father, since a Son must have a Father. Confession of Son and Father are thus strictly correlative – confession of either entails confession of both.