And we have believed and known. The verbs are in the past tense, but they may be changed into the present tense, we believe and know, but it makes little difference in the meaning. In these words Peter gives a brief summary of faith. But the confession appears to have nothing to do with the matter in hand, for the question had been raised about eating the flesh of Christ. I reply, although the twelve did not at once comprehend all that Christ had taught, yet it is enough that, according to the capacity of their faith, they acknowledge him to be the Author of salvation, and submit themselves to him in all things. The word believe is put first, because the obedience of faith is the commencement of right understanding, or rather, because faith itself is truly the eye of the understanding. But immediately afterwards knowledge is added, which distinguishes faith from erroneous and false opinions; for Mahometans and Jews and Papists believe, but they neither know nor understand any thing. Knowledge is connected with faith, because we are certain and fully convinced of the truth of God, not in the same manner as human sciences are learned, but when the Spirit seals it on our hearts.

We are sure - See a similar confession of Peter in Matthew 16:16, and the notes at that place. Peter says we are sure, in the name of the whole of the apostles. Jesus immediately cautions him, as he did on other occasions, not to be too confident, for one of them actually had no such feelings, but was a traitor.

We believe - On the authority of thy word; and are sure - have known, εγνωκαμεν, by the evidence of thy miracles, that thou art the Christ, the promised Messiah. And we belyfath and witen that thu eart Crist Godes Son. Anglo-Saxon. How near is the mother to the daughter tongue!
Instead of Christ the Son of the living God, some excellent MSS., BCDL, and others, read ὁ αγιος του Θεου, the holy one of God; and this reading Griesbach has received into the text, leaving out του ζωντος, the living. Χριστος, and ἁγιος convey nearly the same meaning; but the Ethiopic, as usual, retains both. Του ζωντες is omitted by BCDL, H, the Coptic, Sahidic, Armenian, later Persic, Vulgate, all the Itala but one, and by the Anglo-Saxon; which last Griesbach has not noticed.

And we believe and are sure,.... Or know of a certainty: they believed upon the first call of them by Christ, and their following of him, that he was the true Messiah; and they came to an assurance of it, by the miracles he wrought, and by the doctrines which he taught; their faith, how weak soever it might be at first, rose up to a full assurance of faith, and of understanding; there was a reality and a certainty in it, as there is in all true faith, with respect to the object, though not always with respect to interest in it; which was the case here, as appears by what follows:
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.

And we believe,--(See on Matthew 16:16). Peter seems to have added this not merely--probably not so much--as an assurance to his Lord of his heart's belief in Him, as for the purpose of fortifying himself and his faithful brethren against that recoil from his Lord's harsh statements which he was probably struggling against with difficulty at that moment. Note.--There are seasons when one's faith is tried to the utmost, particularly by speculative difficulties; the spiritual eye then swims, and all truth seems ready to depart from us. At such seasons, a clear perception that to abandon the faith of Christ is to face black desolation, ruin and death; and on recoiling from this, to be able to fall back, not merely on first principles and immovable foundations, but on personal experience of a Living Lord in whom all truth is wrapt up and made flesh for our very benefit--this is a relief unspeakable. Under that blessed Wing taking shelter, until we are again fit to grapple with the questions that have staggered us, we at length either find our way through them, or attain to a calm satisfaction in the discovery that they lie beyond the limits of present apprehension.

And we - Who have been with thee from the beginning, whatever others do, have known - Are absolutely assured, that thou art the Christ.