Tim Keller, in his article titled Preaching in a Secular Culture, points out a distinction that Jonathan Edwards (1703-1757) made between what is useful and what is beautiful and this respect to nominal Christians and authentic Christians. Keller states,
“Edwards defined a nominal Christian as one who finds Christ useful, while a true Christian is one who finds Christ beautiful for who He is in Himself.”
*Note: I just finished reading the article a few days ago. It is a remarkably good article. I strongly recommend reading it.