Mack, having struggled with drug abuse and sexual sin, was desperate. Relationships that he valued were in disarray and his conscience was beating him up. In his misery, he found himself unannounced at a church asking to speak with a pastor. There he found relief in sharing his complicated story and in hearing about God’s mercy and forgiveness.

Psalm 32 is believed to have been composed by David after his sexual sin. He compounded his wrongdoing by devising a sinister strategy that resulted in the death of the woman’s husband (see 2 Samuel 11–12). While these ugly incidents were behind him,…