What is the Church that Jesus Built?

"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"

What does "rock" refers to? What is a "church"?

Let me quote a Old Testament verse for the New Testament was build upon Laws, Writings, and Prophecies, which were fulfilled through Jesus Christ. "The Lord is my ROCK, and my fortress, and my deliver. My God, is the ROCK of refuge." -Psalm 18:2 & 94:22

Oh boy, I wish I could be a wonderful coach like Him! Jesus knew what he needed to say after Peter proclaimed that he is the Christ. He encouraged Peter, "through this obedience my Father and I will build you up." Peter was willingly to look foolish, opening up the opportunity for himself to be molded by God. God protects and nurtures us through the Words, through the community of Christ, and through being personally taught by Him.

Through that process, we may be either "be tossed about by every wind of doctrine" or "build on the rock" of Christ's truth in love. We would surely sink when we paid attention to the wind around us like how Peter once sank. He learned to keep his eyes upon the Rock after this experience. May we learn to lay down our doctorines and keep our eyes on Jesus, our sole Rock.