"'Food for the stomach and the stomach for food' - but God will destroy them both. The body is not meant for sexual immorality, but for the Lord, and the Lord for the body." NIV translation
Many people use the excuse "That's the way God made me" to explain their sinful ways and to give them a reason to continue in sin. Although it is true that God made us, He did not make us to lead sinful lives. We were meant to be with God and to serve Him which is not possible if we are wallowing in sin.
"By his power God raised the Lord from the dead, and he will raise us also." NIV translation
Our hope, as believers in Jesus Christ, is that we will be raised from the dead to live with God forever. This includes a raising of the body just as it was with Jesus. Therefore, why would we want to defile this body with sexual immorality?
"Do you not know that your bodies are members of Christ himself? Shall I then take the members of Christ and unite them with a prostitute? Never!" NIV translation
Paul reasons with the Corinthians by asking them these questions. His goal is to get them to see how ridiculous it would be for a part of Christ to lay with a prostitute. The same principle applies to all sin and the simple fact is that, as a part of the body of Christ, it does not make any sense for us to continue in sin.
"Do you not know that he who unites himself with a prostitute is one with her in body? For it is said, 'The two will become one flesh.'" NIV translation
Paul quotes from Genesis 2:24 where God gave Eve to Adam in marriage. The simple fact of the matter is that, in God's eyes, when a man and woman have sexual relations they are married and become one.
"But he who unites himself with the Lord is one with him in spirit." NIV translation
When we accept Jesus Christ as our Lord and Savior, He comes and lives inside of us through the Holy Spirit. We become one with Him in that He will guide our every step and even our every thought if we are focused on Him.