Jamieson, Fausset & Brown

And Simon Peter answered and said, Thou art the Christ, the Son of the living God--He does not say, "Scribes and Pharisees, rulers and people, are all perplexed; and shall we, unlettered fishermen, presume to decide?" But feeling the light of his Master's glory shining in his soul, he breaks forth--not in a tame, prosaic acknowledgment, "I believe that Thou art," &c.--but in the language of adoration--such as one uses in worship, "THOU ART THE CHRIST, THE SON OF THE LIVING GOD!" He first owns Him the promised Messiah (see on Mat 1:16); then he rises higher, echoing the voice from heaven--"This is My beloved Son, in whom I am well pleased"; and in the important addition--"Son of the LIVING GOD"--he recognizes the essential and eternal life of God as in this His Son--though doubtless without that distinct perception afterwards vouchsafed.