Paraphrase. 'It is true as you suggest that “all things are lawful” but this is not an absolute but a relative principle. You must not argue that the existence of appetites proves the lawfulness of their gratification: you must take care that what is lawful is also wise, and that appetite does not make you its slave. (13, 14) Both food and the organ which digests it are perishable. But the body has an eternal element, and unchastity harms that eternal element, designed as it is for the service of Christ and participation in the Resurrection. (15-17) You know that your bodies partake in the mystic union that exists between Christ and His people. How shameful is it, therefore, to violate this union by acts of immorality. Such acts cause a carnal union between those who participate in them, just as Scripture speaks of husband and wife being "one flesh": whereas the Christian is united to Christ in a spiritual union. And the immoral union is destructive of the spiritual union. (18, 19) Therefore keep yourselves unspotted by this sin; for there is none that defiles the body like this and makes it unfit for the dwelling-place of the Holy Spirit. (20) Remember that you are not your own possession; you have been purchased by Christ who has given His life for you; therefore, see that you honour Him by consecrating your very bodies to His service.'
1 Corinthians 6:12-20
12 All things are lawful unto me, but all things are not expedient: all things are lawful for me, but I will not be brought under the power of any.
13 Meatsa for the belly, and the belly for meats: but God shall destroy both it and them. Now the body is not for fornication, but for the Lord; and the Lord for the body.
14 And God hath both raised up the Lord, and will also raise up us by his own power.
15 Know ye not that your bodies are the members of Christ? shall I then take the members of Christ, and make them the members of an harlot? God forbid.
16 What? know ye not that he which is joined to an harlot is one body? for two, saith he, shall be one flesh.
17 But he that is joined unto the Lord is one spirit.
18 Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body.
19 What? know ye not that your body is the temple of the Holy Ghost which is in you, which ye have of God, and ye are not your own?
20 For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God's.