His was the title of father of the Son of God, because he was the Spouse of Mary, ever Virgin. He was our Lord’s father, because Jesus ever yielded to him the obedience of a son. He was our Lord’s father, because to him were entrusted, and by him were faithfully fulfilled, the duties of a father, in protecting Him, giving Him a home, sustaining and rearing Him, and providing Him with a trade (Saint John Henry Newman, +1890)