Thomas Aquinas Commentary 1 Corinthians 6:13-20

"Meats for the belly, and the belly for meats: but God shall bring to nought both it and them. But the body is not for fornication, but for the Lord; and the Lord for the body: and God both raised the Lord, and will raise up as through his power. Know ye not that your bodies are members of Christ? shall I then take away the members of Christ, and make them members of a harlot? God forbid. Or know ye not that he that is joined to a harlot is one body? for, The twain, saith he, shall become one flesh. But he that is joined unto the Lord is one spirit. Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body. Or know ye not that your body is a temple of the Holy Spirit which is in you, which ye have from God? and ye are not your own; for ye were bought with a price: glorify God therefore in your body." — 1 Corinthians 6:13-20 (ASV)

After rebuking the Corinthians about lawsuits, the Apostle now returns to condemn the sin of sexual immorality, which he mentioned in 1 Corinthians 5:11 and in judging which the Corinthians had been negligent. He condemns sexual immorality for four reasons: first, based on God’s design; secondly, from our union with Christ (verse 16); thirdly, from the defilement of the body (verse 18); and fourthly, from the dignity of grace (verse 19). Regarding the first reason, he does two things: first, he presents God’s design; secondly, the purpose of that design (verse 14).

Regarding the first point, it should be noted that some people justify their immoral conduct by appealing to God’s design. They argue that those who engage in sexual immorality are using their bodies for a purpose established by God. But the Apostle refutes this, saying that while food is meant for the stomach and the stomach for food, the human body is not meant for sexual immorality but for the Lord. That is, it was designed to belong to the Lord Jesus Christ, and the Lord, in turn, for the body. This means Jesus Christ was given to humanity so that our bodies might be conformed to His glory, as it says in Philippians 3:21: He will change our lowly body to be like His glorious body.

An objection might be raised against this: just as the stomach is designed for the use of food, so also are certain parts of the human body designed by God for procreation—namely, the very parts used in sexual immorality. However, we must pay attention to the difference between these two cases. First, the Apostle was speaking about a single part of the body, the stomach, but here he speaks of the entire body. The whole body is not designed for sexual immorality any more than it is designed for merely eating food. Rather, food is used for the body’s benefit, and the body exists for the sake of the soul, from which it receives life according to its state. And since all things are ordered toward God as their ultimate purpose, the body should be subject to the Lord and dedicated to Him.

Furthermore, when the Apostle spoke of eating, he referred to it in general terms, not in a disordered way. Sexual immorality, however, is a disordered use of the members involved. Therefore, these members exist not for sexual immorality but for procreation as ordered by reason, which the body’s members should serve. In the same way, the stomach is not for gluttony and drunkenness, but for the proper use of food.

Then, when he says, and God raised the Lord, he points to the purpose of the design mentioned above. First, he indicates what God has done for the Lord, saying, And God raised the Lord—that is, the Lord Jesus Christ—from the dead, for which Christ Himself petitions in Psalm 41:10: Do thou, O Lord, be gracious to me and raise me up. Now, God is the Father, the Son, and the Holy Spirit; therefore, Christ Himself, who is the Son of God, also raised Himself and rose by His own power, as it says in Psalm 3:5: I will lie down and sleep; I wake again, for the Lord sustains me, and in 2 Corinthians 13:4: He was crucified in weakness, but lives by the power of God. Secondly, he indicates what God will do for us, saying, God will also raise us up by his power, the same power by which He raised Christ, as it says in Romans 8:11: He who raised Christ Jesus from the dead will give life to your mortal bodies.

It should be noted that when speaking earlier about food and the stomach, which relate to our physical life, the Apostle said that God would destroy them. But now, speaking of the body and the Lord, he mentions the resurrection, because when this physical life ends, the nature of the body will be transformed into something better. Therefore, it is clear that the body should not be used for sexual immorality, which hinders future incorruptibility, according to Galatians 6:8: He who sows to his own flesh will from the flesh reap corruption.

Then, when he says, Do you not know, he presents a second reason, which is based on the human body’s union with Christ. Specifically, the members of a man who engages in sexual immorality become the members of a prostitute, but a man’s members are Christ’s members. Therefore, through sexual immorality, Christ’s members become the members of a prostitute, which is improper. Regarding this point, he does four things. First, he presents the major premise, saying, Do you not know that your bodies are members of Christ? It is as if he is saying: You should not be ignorant of this, because all of you who have been reborn in Christ have become members of Christ, as it says later in 1 Corinthians 12:27: Now you are the body of Christ and individually members of it. This is true not only of your souls, which are justified by Him, but also of your bodies, which will be raised up by Him, as was stated earlier.

Secondly, he presents the conclusion, saying, Shall I take the members of Christ—that is, remove them from the service of Christ to whom they should be dedicated, as it says in Romans 6:13, Yield your members to God as instruments of righteousness—and make them be members of a prostitute by fornicating? Never! For this is a horrible sacrilege. Thus it says in Malachi 2:11: Judah has profaned the sanctuary of the Lord which he loves and has married the daughter of a foreign god.

Thirdly, he presents the minor premise, saying, Do you not know that he who joins his body to a prostitute... becomes one body with her?—that is, through an unclean union. To prove this, he appeals to the authority of Genesis, saying, For it is written, namely in Genesis 2:24, the two... become one flesh. This means that through physical union they are made one flesh, and so the members of one become the members of the other. These are Adam’s words about a husband and wife, which the Apostle here applies to sexual immorality because there is no specific difference between the physical acts themselves. It should be noted that, as the Philosopher says in the book, On the Generation of Animals, the active principle of generation is in the male, and the passive principle is in the female. And just as in a plant, whose life is ordered chiefly toward generation, there is always one body in which both principles are united, so it is in animals, which are ordered toward higher acts of life. In them, there is not always one body containing both principles; instead, one is made from two in the act of generation. In the case of humans, it is not only the man’s body that is involved, because as it says later in 1 Corinthians 7:4: The husband does not have rule over his own body, but the wife has.

He then proves the minor premise in another way, saying, But he who is united to the Lord... is one spirit with him. This union is by faith and love, and it is a spiritual, not a physical, unity. Thus it says in Romans 8:9: Anyone who does not have the Spirit of Christ does not belong to him, and in John 17:21: that they may be one in us, as we are one—that is, by a connection of the Spirit. And because the body serves the spirit, it follows that our bodies are also members of Him to whom we are united by the Spirit—not, of course, through a physical union, but a spiritual one. From the two points given above, a single reason can be formed: because our body is not destined for sexual immorality but for the Lord, and because our members are Christ’s members (as he explains later), we must not make them the members of a prostitute by engaging in sexual immorality.

Then, when he says, Flee fornication, he presents a third reason, which is based on the body’s defilement. First, he presents the command: Flee fornication. Here it should be noted that other vices are overcome by resisting them. This is because the more a person considers the details of those sins, the less he will find in them to enjoy and the more he will find to be cautious about. But the vice of sexual immorality is not overcome by resisting it in the same way, because the more a person considers the specific situation, the more he is inflamed with passion. Instead, it is overcome by fleeing—that is, by completely avoiding all impure thoughts and all occasions for sin, for it says in Zechariah 2:6: Flee from the land of the north.

Secondly, he gives the reason, saying, Every other sin a man commits is outside the body. To understand this, it should be noted that some sins do not culminate in physical pleasure but only in a spiritual one; these are called spiritual sins, such as pride, greed, and spiritual apathy. Sexual immorality, however, is entirely completed in physical pleasure. According to this interpretation, the phrase Every other sin a man commits is outside the body means that it is completed outside the pleasure of the body. But the sexually immoral person sins against his own body because the sin is completed in the flesh.

However, the fact that the sin of gluttony also culminates in bodily pleasure seems to contradict the explanation above. One possible answer is that gluttony is considered a form of lust, insofar as it leads to it, as it says in Ephesians 5:18: And do not get drunk with wine, for that is debauchery. But a better explanation is that the Apostle is not saying that the sexually immoral person sins with his own body (which would fit the first explanation), but that he sins against his own body by corrupting and defiling it beyond the bounds of reason. Thus it says in Revelation 3:4: You still have a few names in Sardis, people who have not soiled their garments, and in Revelation 14:14: It is these who have not defiled themselves with women.

Alternatively, according to Augustine, a person who engages in sexual immorality sins against his own body because his soul is so completely subjected to the flesh in that act that it cannot think of anything else at that time. As it says in Psalm 32:9: Be not like a horse or a mule, without understanding.

Another interpretation is that he sins against his own body—that is, against his wife, who is called the husband’s body. Other sins are not as directly opposed to her as the husband’s sexual immorality is. Thus it says in 1 Thessalonians 4:4: That each one of you know how to take a wife for himself in holiness and honor.

Yet another interpretation from Augustine understands this as spiritual immorality, through which the soul clings to the world in love and turns away from God, as it says in Psalm 73:27: Those who are far from you shall perish. The meaning, therefore, would be that whoever commits this spiritual immorality and turns away from God for love of the world sins against his own body—that is, through bodily desire. But every other sin—for example, one committed from forgetfulness, ignorance, or negligence—is outside the body, meaning it is outside of bodily desire.

Then, when he says, Do you not know, he presents the fourth reason, which is based on the dignity of grace. This dignity comes from two sources: the grace of the Holy Spirit and the redemption of Christ’s blood. Regarding this, he does three things. First, he declares the dignity of our body, which it has from the grace of the Holy Spirit, saying, Do you not know—as if to say, you should not be ignorant of this—that your body... is a temple of the Holy Spirit, just as he said earlier in 1 Corinthians 3:16: Do you not know that you are God’s temple? He then gives the reason for this, saying, who is within you. A house of God is called a temple. Therefore, because the Holy Spirit is God, it is correct to say that anyone in whom the Holy Spirit dwells is a temple of God. The Holy Spirit dwells primarily in the hearts of believers, in whom the love of God is poured out by the Holy Spirit, as it says in Romans 5:5. But secondarily, He is also in the members of the body, insofar as they perform acts of love. Thus it says in Psalm 84:2: My heart and my flesh sing for joy to the living God. But so that they would not attribute this dignity to themselves, he adds, which you have from God and not from yourselves. Thus it says in Joel 2:28: I will pour out my Spirit on all flesh.

Secondly, he mentions the dignity our bodies have from the redemption of Christ, saying, You are not your own, but belong to Jesus Christ, as it says in Romans 14:8: Whether we live or whether we die, we are the Lord’s. And in 2 Corinthians 5:15: Those who live no longer live for themselves. He gives the reason for this when he says, You were bought with a great price. Therefore, you are slaves of Him who has redeemed you from the slavery of sin; thus it says later in 1 Corinthians 7:22: For he who was called in the Lord as a freedman is a slave of the Lord; and in Psalm 31:5: You have redeemed me, O Lord, God of truth. The price of redemption is called great because it is not perishable but has everlasting power, since it is the blood of the everlasting God. Thus it says in 1 Peter 1:18: You know that you were ransomed from the futile ways inherited from your fathers, not with perishable things, such as silver and gold, but with the precious blood of Christ.

Thirdly, he draws the intended conclusion, saying, So glorify and carry God in you body. For since your members are a temple of God, nothing should appear in your body except what pertains to God’s glory. This is what it means to glorify God in your body, as it says in Psalm 29:9: In his temple all cry, ‘Glory’; and again, in Exodus 40:34: Then the cloud covered the tent of meeting and the glory of the Lord filled the tabernacle. Furthermore, because you are not your own but are slaves of God, you should carry God as a horse or another animal carries its master. Thus it says in Psalm 73:23: I was like a beast towards you. Our body carries the Lord insofar as it is assigned to a divine ministry. Therefore, a person should avoid sinning against his own body through sexual immorality, which is contrary to the glory of God and to the service our body owes to God.