In this passage, Paul explains that those who do not belong to Christ will not enter into heaven, while those that belong to Christ are supernaturally unlike those who do not. He begins by listing some types of people who will not enter into heaven: fornicators, idolaters, adulterers, effeminate, homosexuals, thieves, covetous, drunkards, revilers, and extortioners. Then, he says that some of the Christians used to be at least some of those types of people. However, they were washed clean of those sins, set apart unto God, and declared righteous by the authority of Jesus Christ, and by the power of the Spirit.
In verse 12, Paul says that all things are lawful for him. This means that all manner of morally neutral things are lawful for him to do. However, not everything benefits people. Furthermore, he has determined not to be enslaved to anything. Then, he begins to apply this rule: food is for the stomach, and the stomach is for food, but both will be destroyed. On the other hand, the entire body is not for sexual immorality, but for the Lord, and the Lord benefits the body. One evidence of this is that God will give Christians glorified bodies, just as He gave Christ a glorified body. Furthermore, Christians’ bodies are members of Christ. Therefore, one should not use something that is united to Christ to be united to a prostitute. The reason for this reality is that sex brings about a union with the two participants. In a spiritual sense, a Christian, who is united to the Lord, is spiritually united to Him in spirit. Therefore, Paul commands the Corinthians, they ought to flee from sexual immorality.
In addition, Paul says that sexual immorality is a unique sin in that the one who commits it sins against his body. This is because the Christian’s body is a dwelling place for the Holy Spirit, and does not belong to him. The reason for this is that he was bought with the price of Christ’s death. Therefore, Paul concludes, Christians ought to glorify God with their bodies.