HIGHLANDS RANCH, Colo. — To many Roman Catholics, especially the older generations, it's inconceivable that online blathering could stand in for confession. "It would be like cheating!" said one woman at St. Mark, in the Denver suburb of Highlands Ranch. But for Ashley Iodice, a high-school senior in Weston, Fla., Internet absolution feels more natural than talking to a priest. Now a Baptist, Iodice grew up Catholic; she remembers confession as scary — and less than sincere. It's hard be honest about the depths of teenage depravity, she said, when you're talking to an elderly priest "who's committed his whole...