1 Corinthians 10:23

All things are lawful for me, but all things are not expedient: all things are lawful for me, but all things edify not (KJV)

Then: Paul returns to a final summary on the topic of eating meat offered to idols. In the beginning he agreed with the liberal Corinthians. Yes they could do it because in their minds the eating meant nothing. Baker (p. 151) adds that Paul draws again upon the pouplar saying "All things are lawful for me" just as he did in 6:12.* Paul showed them the perils of that action- its affect on the lives of others and on their own life if they participated in worship of idols (demons). Here, Paul returns to specifics. He discusses when they can and when they should not eat and most importantly adds in the "why," the rationale for their actions. All things are lawful, but not always expedient and not always edifying. When and how? The following verses explain.At this point in his commentary, N.T. Wright (p. 135) brings out Paul's genius as a teacher, his ability to teach the generalities of the big picture and fill it in with the details of practical everyday applications.

Now: Today's Christians need to search for the parallels. They need to sort out what the law allows as compared to what is useful for missionary work. It is lawful to drink wine, but a disaster for those who can't handle alcohol. It is lawful to buy newspapers or magazines with almost pornographic ads in them, but not wise to leave around for impressionable young minds or those seeking love in wrong places. That's Paul' point for Americans today.

Extra source: Cornerstone Biblical Commentary 1 Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.
* Sayings similar to today's "Everybody does it," "Don't ask, Don't tell," "You can't teach an old dog new tricks," etc.