I noticed in our songbook that a few of the songs written are by Amy Grant. I don't know if you are familiar with her, but she is a singer and songwriter who divorced because of "irreconcilable differences" and promptly remarried. My question is, do you think it is appropriate to sing songs that are written by her during service?
What makes a song appropriate for worship are the words and the ideas they express. I suspect there are a number of songs in our songbook written by people who lived less than exemplary lives. But then I'm also sure there have been good people who have written songs that aren't the best to use because people do make mistakes.
When you know someone hasn't been living up to the standard of Christ, then it means extra care should be taken to see if the teachings in the song are truly accurate or not.
By way of example, when King Solomon was younger, he was inspired by God and wrote many useful things. He wrote some of our Psalms, Proverbs, Ecclesiastes, and the Song of Solomon. When he became an old man, he turned away from God. "But King Solomon loved many foreign women, as well as the daughter of Pharaoh: women of the Moabites, Ammonites, Edomites, Sidonians, and Hittites -- from the nations of whom the LORD had said to the children of Israel, "You shall not intermarry with them, nor they with you. Surely they will turn away your hearts after their gods." Solomon clung to these in love. And he had seven hundred wives, princesses, and three hundred concubines; and his wives turned away his heart. For it was so, when Solomon was old, that his wives turned his heart after other gods; and his heart was not loyal to the LORD his God, as was the heart of his father David" (I Kings 11:1-4). Solomon's sin late in life does not detract from the inspired work that he wrote earlier in his life.
Not that it makes much difference, but the one song by Amy Grant that is in our hymnal, "Thy Word," was written in 1984, long before her 1999 divorce from her husband. Still, it is because of her denominational background that not many of her songs are used in the church because many of them contain biblical inaccuracies.