First Corinthians 6:12 through 20 adds considerable light to the matter of the believers’ body. We will now briefly consider this portion verse by verse.
Verse 12 says, "All things are lawful to me, but not all things are profitable; all things are lawful to me, but I will not be brought under the power of anything." The apostle was talking about the question of the body. (This will be explained later.) He said that everything is lawful because, according to nature, all the desires of the body, such as eating, drinking, sex, etc. (v. 13), are natural, necessary, and lawful. But he said that these things (1) are not all expedient and (2) should not bring people under their power. In other words, there are many things, humanly speaking, that a believer can do related to his body but may choose not to do because he belongs to the Lord and wants to glorify God.
Verse 13 says, "Foods are for the stomach, and the stomach for foods; but God will bring to nought both it and them. But the body is not for fornication but for the Lord, and the Lord for the body." The first half of this verse is paired with the first half of the last verse. Food is lawful, but food and the belly will both be brought to nothing. Therefore, not all are expedient. The last half is also paired with the last half of the last verse. A believer can be completely free from the control of sexual lusts and offer his body completely to the Lord (7:34).
"The body is...for the Lord." This statement is very crucial. The apostle has just spoken on the problem of food. The matter of eating and drinking provides believers with an opportunity to carry out the instruction, "The body is...for the Lord." The original cause of man’s fall was food. The Lord Jesus was also tempted by food in the wilderness. Many Christian believers do not know they should glorify God in the matter of eating and drinking. They do not consider that the purpose of eating and drinking is only to make the body fit for the Lord’s use. They eat and drink to satisfy their own desires. We should know that the body is "for the Lord" and not for ourselves. Therefore, we should not use our body to please ourselves. Eating and drinking should not hinder our fellowship with God; they should only preserve our body in its normal condition.
The apostle also spoke on the question of fornication. This kind of sin defiles the body. Therefore, it is absolutely contrary to the teaching of "the body is...for the Lord." The fornication mentioned here does not include only the indulgence of the lust of the flesh outside of marriage, but also between a husband and a wife. The body is for the Lord; this means that the body is completely for the Lord and not for one’s self. Therefore, lawful indulgence should also be forbidden.
The apostle wants us to see that everything that passes the limit or ignores the limit—no matter what it may be—ought to be resisted absolutely. Since the body is for the Lord, no one ought to use the body in addition to the Lord. Whoever employs the body, no matter what part, for his own pleasure, does not please God. In addition to being a vessel for righteousness, the body should not serve any other purpose. The body, like our person, should not serve two masters. Even though food and sex are matters of nature, we can only allow them to be satisfied when need arises. When the need is met, the body is still for the Lord, not for food and sex. Today many Christian believers pursue only after the sanctification of their spirit and soul, but do not know that in order to attain sanctification of their spirit and soul, they must attain sanctification in their body. In many respects the sanctification of the spirit and soul depends on the sanctification of the body. They forget that all of their nerves, sensations, activities, living, working, eating, drinking, speaking, etc., should be for the Lord. Otherwise, they will not arrive at perfection.
(Spiritual Man, The (3 volume set), Chapter 39, by Watchman Nee)