One level of this concept of responsibility to the body is, of course, taking care of our physical bodies. Because we belong to God and are therefore holy and are integral parts of the body of Christ, this responsibility weighs upon us with greater intensity than upon those who are not. In John 14:23, Jesus introduces the basis for this concept to illustrate the closeness of our relationship with God: "If anyone loves Me, he will keep My word; and My Father will love him, and We will come to him and make Our home with him." Under the Old Covenant, God is mysterious and distant and dwelling in the Temple. Under the New Covenant, we become the Temple, and God becomes knowable and personal.
In I Corinthians 6:15-20, Paul clearly confirms these concepts:
Do you not know that your bodies are members of Christ? Shall I then take the members of Christ and make them members of a harlot? Certainly not! Or do you not know that he who is joined to a harlot is one body with her? For "The two," He says, "shall become one flesh." But he who is joined to the Lord is one spirit with Him. Flee sexual immorality. Every sin that a man does is outside the body, but he who commits sexual immorality sins against his own body. Or do you not know that your body is the temple of the Holy Spirit which is in you, which you have from God, and you are not your own? For you were bought at a price; therefore glorify God in you body and in your spirit, which are God's.
It is difficult to imagine how much more clearly he could express our responsibility to maintain good health! It is actually a fourfold responsibility:
1. To God because He bought us at a price;
2. To Jesus Christ because we are part of His body;
3. To ourselves to come out of sin; and
4. To our loved ones to serve them.
Meeting all of these glorifies God. Paul's concern is that debauching the body by involving it in sin threatens the continuation of the relationships. We normally think of sin as breaking a law. This is not a wrong understanding, but the Bible's usage is much broader. Biblically, sin is falling short of the glory of God, or turning aside from the path of what is right. It is also missing the mark. Sin is the Bible's term to indicate a failure to do things right, and right is the way God would do it. Of course, some failures to do what is right are far more serious than others are.
— John W. Ritenbaugh