The Head of Christ is God the Father is obvious form scriptures because Jesus worships God his Father. Jesus worships, glorifies, honours YHWH as his God and Father. Jesus prays and sings to YHWH his God and Father.
Trinity incorrectly teaches that the Father and son are co-equal thereby insulting the God, Jesus came to preach. Trinity will teach you to resist the Father, therefore you will neither understand the son nor the Father.