For who is God besides the Lord? And who is the Rock except our God? (Ps. 18:31)(NIV)
We often hear that the Lord is our rock, but we don't always realize what this means. A rock in ancient Israel provided security in two ways: It served as a bulwark against attacking armies, and it provided an immovable foundation for great buildings. David realized that God was an unshakeable foundation for his faith, and he often ran to this refuge to regain his strength. We can find our security in the Lord as well. Let us praise God that He is our rock, upon which we can confidently build our life and faith.
O God our Rock, our hope rests in you. We praise you for your strength, and we thank you for the security we can find in you. Teach us to build our faith upon you, for you are unshakeable. Amen.
(from the Praise & Worship Study Bible -Tyndale House)