On the significance of Peter’s confession, these notes say, “All who confess Jesus as the Messiah, the Son of the Living God, are likewise blessed.” The same notes explain the two Greek words for pebble and stone, or bedrock, in Matthew 16.
Except Jesus spoke in Aramaic where just one word for rock was used "kepha" hence his name is Cephas, which is translated as Petros in Greek (masculine singular noun) which gives us the English name Peter. The notes in that bible are inaccurate.
Greek: Kago.
And I say to thee, and tell thee why I before declared, (Joh 1:42) that thou shouldst be called Peter, for thou art constituted the rock upon which, as a foundation, I will build my Church, and that so firmly, as not to suffer the gates (i.e. the powers) of hell to prevail against its foundation; because if they overturn its foundation, (i.e. thee and thy successors) they will overturn also the Church that rests upon it. Christ therefore here promises to Peter, that he and his successors should be to the end, as long as the Church should last, its supreme pastors and princes. (Tirinus)
--- In the Syriac tongue, which is that which Jesus Christ spoke, there is no difference of genders, as there is in Latin, between patra, a rock, and Petrus, Peter; hence, in the original language, the allusion was both more natural and more simple. (Bible de Vence)
--Thou art Peter;[2] and upon this (i.e. upon thee, according to the literal and general exposition of the ancient Fathers) I will build my church. It is true St. Augustine, in one or two places, thus expounds these words, and upon this rock, (i.e. upon myself: ) or upon this rock, which Peter hath confessed: yet he owns that he had also given the other interpretation, by which Peter himself was the rock. Some Fathers have also expounded it, upon this faith, which Peter confessed; but then they take not faith, as separated from the person of Peter, but on Peter, as holding the true faith. No one questions but that Christ himself is the great foundation-stone, the chief corner-stone, as St. Paul tells the Ephesians; Chap. ii, ver. 20.) but it is also certain, that all the apostles may be called foundation-stones of the Church, as represented Rev 21:14 In the mean time, St. Peter (called therefore Cephas, a rock) was the first and chief foundation-stone among the apostles, on whom Christ promised to build his Church. (Witham)
--- Thou art Peter, &c. As St. Peter, by divine revelation, here made a solemn profession of his faith of the divinity of Christ, so in recompense of this faith and profession, our Lord here declares to him the dignity to which he is pleased to raise him: viz. that he, to whom he had already given the name of Peter, signifying a rock, (Joh 1:42) should be a rock indeed, of invincible strength, for the support of the building of the church; in which building he should be next to Christ himself, the chief foundation-stone, in quality of chief pastor, ruler, and governor; and should have accordingly all fulness of ecclesiastical power, signified by the keys of the kingdom of heaven.
--- Upon this rock, &c. The words of Christ to Peter, spoken in the vulgar language of the Jews, which our Lord made use of, were the same as if he had said in English, Thou art a rock, and upon this rock I will build my church. So that, by the plain course of the words, Peter is here declared to be the rock, upon which the church was to be built; Christ himself being both the principal foundation and founder of the same. Where also note, that Christ by building his house, that is, his Church, upon a rock, has thereby secured it against all storms and floods, like the wise builder. (Mat 7:24-25.)
--- The gates of hell, &c. That is, the powers of darkness, and whatever Satan can do, either by himself or his agents. For as the Church is here likened to a house, or fortress, the gates of which, i.e. the whole strength, and all the efforts it can make, will never be able to prevail over the city or Church of Christ. By this promise we are fully assured, that neither idolatry, heresy, nor any pernicious error whatsoever shall at any time prevail over the Church of Christ. (Challoner)
--- The gates, in the Oriental style, signify the powers; thus, to this day, we designate the Ottoman or Turkish empire by the Ottoman port. The princes were wont to hold their courts at the gates of the city. (Bible de Vence)
[BIBLIOGRAPHY]
St. Augustine, serm. 13, de Verbis Domini, in the new edit. serm. 76. t. v. p. 415, expounds these words super hanc Petram, i.e. super hanc Petram, quam confessus es, super meipsum. See also tract. 24. in Joan, t. iii. p. 822. But he elsewhere gave the common interpretation, as he says, lib. i. Retrac. and in Psal. lxix. Petrus, qui paulo ante Christum confessus erat filium Dei, & in illa Confessione appellatus erat Petra, super quam fabrificatur Ecclesia, &c. See St. Jerome on this place, lib. iii. p. 97. ædificabo (inquit Christus) super te Ecclesiam meam. (St. John Chrysostom hom. lv. in Matt. &c.)
