Matthew 3:17

This most solemn testimony of God the Father, relative to his own beloved Son, is repeated below in chap. xvii; and is of such great moment, that the Holy Ghost would have it repeated not only by three evangelists, Matthew, Mark and Luke, but also by St. Peter, as a fourth evangelist, 2nd epistle chap. i. (Tirinus) --- In Greek, the emphatic article Greek: o uios mou o agapetos, strengthens the proof that Jesus Christ, upon whom the Spirit of God descended in the shape of a dove, was not the adoptive, but natural Son of God, born of Him before all ages, and should silence every blasphemous tongue and pen that can attempt to rob Jesus Christ of his divinity, and poor man of all hopes of salvation, through this God-man, Christ the Lord. But if it here be asked, why Jesus Christ, who was innocence itself, yes, and the very essence of sanctity, condescended so far as to be baptized with sinners, we answer, with the Holy Fathers, that it was, 1. to sanction the baptism and ministry of his precursor; 2. not to lose this opportunity of teaching humility, by placing himself among sinners, as if he had stood in need of the baptism of penance for the remission of sins; and lastly, with St. Ambrose, that it was to sanctify the waters, and to give to them the virtue of cleansing men from their sins by the laver of baptism. (Haydock)