Many of the problems in the first-century Corinthian church involved the Corinthian believers’ not living according to who they truly were in Christ. We have seen this already in 1 Corinthians 5:6–8, where the church’s refusal to deal rightly with the man in an incestuous relationship with his stepmother was really a failure of the community to recognize that it was unleavened (holy) and therefore had to get rid of any leaven (unholiness) among them. Such failures to live up to who they were in Christ should be kept in mind as Paul begins his next section of instruction in 6:12. The Apostle has already told them that in Christ they have been transformed and have left their unclean past behind (vv. 9–11). Now, they must put that holiness into practice.
One area where the Corinthians were failing was in sexual matters, which Paul takes up in the second half of chapter 6 (see v. 13). To launch this discussion, the Apostle quotes the phrase “all things are lawful for me,” which was almost certainly a slogan used by some in the Corinthian church. The catchphrase was a declaration of libertinism. The Corinthians had a false view of Christian liberty, believing that since they were not under the Mosaic law, just about anything they wanted to do was permissible. This was a common misunderstanding of Paul’s teaching, as is evident in texts such as Romans 6:15.
Of course, freedom from the law entails freedom from its condemnation, not freedom from any obligation to keep God’s commandments. Thus, Paul answers the Corinthians’ sloganeering by noting that if we think we may do whatever our fallen hearts desire, we will do things that are not helpful—beneficial—to others, and we will end up enslaved to what we sinfully pursue (1 Cor. 6:12). He goes on in verse 13 to quote another slogan, which actually states, “Food is meant for the stomach and the stomach for food—and God will destroy both one and the other.” (Note that many commentators believe the entire statement is a Corinthian slogan, thus the different placement of the quote marks than the ESV.) Apparently, the Corinthians also used this phrase to justify their libertinism. It seems they made a radical distinction between the body and the soul, saying that since God would destroy the body but not the soul, they could do what they wanted with their physical bodies without harming the soul. Paul will not let them make this conclusion, for our bodies belong to the Lord and must be regulated by His commandments (v. 13).