In his book, What Is the Meaning of Sex? (Crossway, 2013), Denny Burk explains why it is contrary to Paul’s intended meaning for us to cite “all things are lawful” (1 Cor. 6:12) as if it is something he approves. In fact, the context makes clear that this is actually something he is refuting:
Almost every modern translations and a near consensus of commentators treat “all things are lawful” not as Paul’s words but as a slogan that Corinthian men used to justify their visits to prostitutes (cf. 1 Cor. 6:15). The NIV captures the correct interpretation: “‘I have the right to do anything,’ you say—but not everything is beneficial. ‘I have the right to do anything’—but I will not be mastered by anything” (1 Cor. 6:12).
. . . [T]he Corinthians had twisted Paul’s law-free gospel into a justification for bad behavior. Thus the phrase “all things are lawful” is not an expression of Christian freedom from the apostle Paul but rather an expression of antinomianism from fornicators! Paul’s aim in 1 Corinthians 6:12-20 is to correct the Corinthians’ misunderstanding. One of the reasons for the Corinthian error was the fact that they viewed the physical body as inconsequential in God’s moral economy (see 1 Cor. 6:13b). Yet Paul refutes the Corinthians on this point and gives them an ultimate ethical norm with respect to their bodies: “You have been bought with a price: therefore glorify God in your body” (1 Cor. 6:20). . . . Paul’s question is not “Is it lawful?” but “Does it glorify God with my body?”
This is not to say that every evangelical who uses this phrase has the wrong general idea. Christian freedom is a legitimate doctrine, rightly interpreted and applied. But I think it’s fairly clear that this is an example of a legitimate intention from the wrong text.