matthew 16:18 And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it. - Free Bible Online

      18. And I say also unto thee--that is, "As thou hast borne such testimony to Me, even so in return do I to thee."
      That thou art Peter--At his first calling, this new name was announced to him as an honor afterwards to be conferred on him (Joh 1:43). Now he gets it, with an explanation of what it was meant to convey.
      and upon this rock--As "Peter" and "Rock" are one word in the dialect familiarly spoken by our Lord--the Aramaic or Syro-Chaldaic, which was the mother tongue of the country--this exalted play upon the word can be fully seen only in languages which have one word for both. Even in the Greek it is imperfectly represented. In French, as WEBSTER and WILKINSON remark, it is perfect, Pierre--pierre.
      I will build my Church--not on the man Simon Bar-jona; but on him as the heavenly-taught confessor of a faith. "My Church," says our Lord, calling the Church HIS OWN; a magnificent expression regarding Himself, remarks BENGEL--nowhere else occurring in the Gospels.
      and the gates of hell--"of Hades," or, the unseen world; meaning, the gates of Death: in other words, "It shall never perish." Some explain it of "the assaults of the powers of darkness"; but though that expresses a glorious truth, probably the former is the sense here.

JFB.