Each person knows that now his body is the temple of God: "Do you not know that your body is a temple of the Holy Spirit, who is in you, whom you have received from God?" (1 Cor. 6:19). Indeed it is. "Don't you know that you yourselves are God's temple and that God's Spirit lives in you?" (1 Cor. 3:16). Okay—each of us is now the temple of God. So where, then, is the Holy of Holies? Your heart.
That's right—your heart. Paul teaches us in Ephesians that "Christ may dwell in your hearts by faith" (3:17). God comes down to dwell in us, in our hearts. Now, we know this: God cannot dwell where there is evil. "You are not a God who takes pleasure in evil; with you the wicked cannot dwell" (Ps. 5:4). Something pretty dramatic must have happened in our hearts, then, to make them fit to be the dwelling place of a holy God.
Of course, none of this can happen for us until we give our lives back to God. We cannot know the joy or the life or the freedom of heart I've described here until we surrender our lives to Jesus and surrender them totally. Renouncing all the ways we have turned from God in our hearts, we forsake the idols we have worshiped and given our hearts over to. We turn, and give ourselves body, soul, and spirit back to God, asking him to cleanse our hearts and make them new.