All human beings are the offspring of the One God Who, we now know more clearly in the the New Testament, is Father, Son and Holy Spirit (Acts 17) In Luke's genealogy Adam is called the Son of God (only an analogy of the eternal Sonship of the Son of God, of course) Mankind is now alienated from the Fatherhood of God by sin, of course.
Christ is the Son of God as eternally generated from the Father, and since the incarnation, as to His human nature.
Believers are the offspring of Christ and the Church. Christ is their Father and the Church is their Mother.
Christ came to reveal not only God the Son, but also God the Father and God the Holy Spirit. Only One Man rather than three was needed for this since God is one in His essence.
The One God is the Everlasting Father of Mankind and believers are restored to the place of sons of the One God by adoption in Christ. They also enter the fellowship of Intertrinitarian Life, so that God the Father is their Father, Christ is their Elder Brother and the Holy Spirit indwells them.
I don't know if this makes things any clearer or if my rambling thoughts on these matters need to be clarified by someone more qualified. Probably the latter.
There are times in the Biblical revelation in which the One God, Father, Son and Holy Spirit is called "Father", and therefore the Son of God Who has the Divine Essence, can also sometimes be apppropriately and without confusion be called Father.
The greater revelation of the Holy Triunity in the New Testament and the greater outpouring of the Spirit means that New Covenant believers can understand and enjoy the Intertrinitarian aspect of fellowship with God in a way that their Old Covenant brothers and sisters didn't.
Bruce and/or Matthew please correct/clarify these thoughts. I feel slightly out of depth.