And Jesus came into the quarters of Cesarea Philippi: and he asked his disciples, saying: "Whom do men say that the Son of man is?" But they said: "Some John the Baptist, and other some Elias, and others Jeremias, or one of the prophets." Jesus saith to them: "But whom do you say that I am?" Simon Peter answered and said: "Thou art Christ, the Son of the living God." And Jesus answering said to him: "Blessed art thou, Simon Bar-Jona: because flesh and blood hath not revealed it to thee, but my Father who is in heaven. And I say to thee: That thou art Peter; and upon this rock I will build my church, and the gates of hell shall not prevail against it. And I will give to thee the keys of the kingdom of heaven. And whatsoever thou shalt bind upon earth, it shall be bound also in heaven: and whatsoever thou shalt loose on earth, it shall be loosed also in heaven." (Matt. 16:13-19)
FAITH IS A GIFT FROM GOD: The natural reason of the people sufficed to make them understand, from His teaching and miracles, that Jesus was a mighty prophet. But, as our Lord expressly said, supernatural light and grace were necessary to enable them to pierce the veil of His human nature, and recognize in this poor Jesus of Nazareth the Second Person of the Blessed Trinity. St. Leo the Great writes thus: "By divine inspiration Peter's mind soared above that which his senses could perceive, and with the eyes of his spirit he recognized the Son of the living God, and the glory of His Divinity."
[From 'A Practical Commentary on Holy Scripture' by Bishop Knecht, D.D.]
(1899 Douay-Rheims Bible)