Pope Saint Leo the Great

And so if anything is rightly done and rightly decreed by us, if anything is won from the mercy of GOD by our daily supplications, it is of his work and merits whose power lives and whose authority prevails in his See. For this, dearly-beloved, was gained by that confession, which, inspired in the Apostle's heart by GOD the Father, transcended all the uncertainty of human opinions, and was endued with the firmness of a rock, which no assaults could shake. For throughout the Church Peter daily says, "Thou art the Christ, the Son of the living GOD," and every tongue which confesses the LORD, accepts the instruction his voice conveys. This Faith conquers the devil, and breaks the bonds of his prisoners. It uproots us from this earth and plants us in heaven, and the gates of Hades cannot prevail against it. For with such solidity is it endued by GOD that the depravity of heretics cannot mar it nor the unbelief of the heathen overcome it.

-- Pope Saint Leo the Great from a sermon