The rock is one of the Bible's favourite names for God's steadfastness: the LORD is my rock, and my fortress. A rock is immovable, reliable, a place of shelter and a firm footing. In the wilderness, God brought water from a rock to save his thirsty people — and Paul says that Rock was Christ, following them through the desert.
Jesus built on the image. The wise man builds his house on the rock, so it stands when the storm comes; and on the rock of Peter's confession — thou art the Christ — he promised to build his church, against which the gates of hell shall not prevail. In a world where everything shifts, the Bible calls the believer to build a life on the one Rock that does not move.
The Rock in Scripture
And did all drink the same spiritual drink: for they drank of that spiritual Rock that followed them: and that Rock was Christ.