"All things are lawful for me," but not all things are helpful. "All things are lawful for me," but I will not be dominated by anything.
"Food is meant for the stomach and the stomach for food"—and God will destroy both one and the other. The body is not meant for sexual immorality, but for the Lord, and the Lord for the body.
1 Corinthians 6:12-13

Many commentators say that "for me, everything is permitted" was a common saying among the Corinthians, not that it was Paul's belief. The Corinthians might have used it in their original letter to Paul. "Food for the stomach and the stomach for food…" may have been another saying among the Corinthians used to justify any and every physical transgression. David Stern says that both of these were evidence of gnostic infiltration. Since the body was neither real nor permanent, nothing you could do to or with the body could possibly have eternal consequences.