In this verse, when St. Paul says that “all things are lawful” he does not refer to things that violate the moral law of God, but rather to those that, while lawful, may not be helpful. For it sometimes happens that what is fine for one causes harm to another. A glass of wine may be good for most, but not for an alcoholic. A few potato chips are a tasty treat, but are not a wise choice for those who struggle to eat them in moderation. Salt and sugar are both gifts of God, but they are not helpful for those with hypertension or diabetes. I love peanut butter, but I cannot eat it in moderation so I don’t eat it at all. Extensive traveling may be fun and enriching, but perhaps not such a good idea for someone who has duties at home to care for children.
Learning that not all things are helpful or expedient saves us a lot of trouble.
Again, St. Paul is not saying that transgressions of the moral law are lawful. He is not saying that promiscuity, wrathful anger, greed, etc. are above criticism. These sorts of things ought to be critiqued, and those who engage in them should be corrected and called to repentance.
But even in the case of lawful pleasures, care should be taken. And thus St. Paul speaks of accepting the fact that not all pleasures are for appropriate for us or to be indulged in just because we want to. Other factors such as health, safety, charity toward others, cost, and the relationship of pleasure to duty may make a particular lawful pleasure inexpedient for us.
I thought of all this as I watched the video below. It features a youngster with a strange horn protruding from his head (perhaps it is the devilish horn of some sin or addiction). He sees others eating ice cream and wants some for himself. But the ice cream man warns the boy that this pleasure is not for him (for some unknown reason related to the horn). This pleasure is lawful, but for the boy it is not expedient.
The youngster has a meltdown in response and the ice cream man relents. As you will see, the boy suffers the ill effects. For as St. Paul says, “All things are lawful for me, but not all things are expedient.”