Thou art that Christ, the Son of the living God, has found its way into this place from the confession of Matthew 16:16. The almost certain reading here is, Thou art the Holy One of God. They had heard this title ascribed to Him by beings from the spirit world (comp. Note on Mark 1:24), and it has been, perhaps, suggested by the present discourse (John 6:32; John 6:46). Like the title Messiah, or Christ, it marks out the consecration to His work. (Comp. John 10:30; 1 John 2:20; Revelation 3:7.) The true reading brings out the successive confessions, which are certainly twice, and probably three times, spoken by Peter. This is the second, coming between that of Matthew 14:33 and that of Matthew 16:16. (See Notes at these places.)
that thou art that Christ; or Messiah, that was promised by God of old, spoken of by the prophets, and expected by the Jews; that anointed prophet Moses had spoken of, that should arise out of Israel, like unto him that anointed priest, who, according to the oath of God, was to be priest for ever, after the order of Melchizedek; and that anointed King, whom God has set over his holy hill of Zion:
the son of the living God; this they knew, and were sure of, both by John's testimony, and by the father's voice from heaven; which three of them heard, at Christ's transfiguration on the mount: God the father is called "the living God"; though the Vulgate Latin version leaves out the word "living"; not to distinguish him from his son; for he also is the living God; and is so called, Hebrews 3:12, but to distinguish him from the idols of the Gentiles, who have no life nor breath in them: and Christ is called the son of the living God, as he is a divine person, as he is truly God; and to show that he has the same life his father has; being a partaker of the same nature, and divine perfections: and this is another reason why sensible souls will go to Christ, and no other; because he is the Messiah, the Saviour, and Redeemer, and an able one; and because he is God, and there is none else.