“God, make me good, but not yet,” Saint Augustine wrote in his 3rd-century autobiography Confessions, forever immortalizing the at-times-contradictory human struggle between good and evil. Indeed, the dramas of saints and sinners are at the heart of the Western art historical canon. Adorning churches, homes and civic spaces, these artworks served to be didactic, devotional, forewarning and entertaining. Sotheby’s Old Masters Online auction (January 21–February 5) presents a trove of images of both the pious and damned. Click ahead to learn their stories. — Kathleen White