Not only interior piety
“For Paul it is all important that the Christian life is not limited to interior piety and cultic acts. One of the most remarkable, and at the same time least known sentences of the Apostle [Paul] runs (1 Cor. 6:13): ‘The body belongs to the Lord, and the Lord to the body’ … Paul does not mean, as Bultmann would have us believe, man’s relation to himself, but that piece of the world which we ourselves are and for which we bear responsibility because it was the earliest gift of our Creator to us … It signifies man in his worldhood and therefore in his ability to communicate [i.e., in his relationality]”
-- E. Käsemann, cited in Thiselton’s superb* commentary on 1 Corinthians
*Superb = I could be stranded on a desert Island with only this book and be reasonably happy.