When Brad Onishi heard that the man accused of a rampage at three Atlanta-area spas told detectives that he had carried out the attacks as a way to eliminate his own temptations, the claim sounded painfully familiar.

Dr. Onishi, who grew up in a strict evangelical community in Southern California that emphasized sexual purity, had spent his teenage years tearing out any advertisements in surfing magazines that featured women in bikinis. He had traded his online passwords with friends to hold himself accountable. “We had a militant vigilance: Don’t let anything in the house that will tempt you sexually,” Dr. Onishi, now an associate professor of religious studies at Skidmore College, recalled.

The evangelical culture he was raised in, he said, “teaches women to hate their bodies, as the source of temptation, and it teaches men to hate their minds, which lead them into lust and sexual immorality.”

Robert Aaron Long, the suspect in the massacres that left eight people dead, told the police this week that he had a “sexual addiction,” and he had been a customer at two of the spas […]