It’s a new year, which means millions of people like you and me are taking time out for some self-reflection. A long look in the mirror—both literal and metaphorical—to find and fix our flaws. When I look in the mirror, past the fingerprints and flecks of toothpaste, what strikes me are the physical signs of sin—the aging image of God that stares back at me. Gray hairs (where hairs may still be found), crow’s feet,...