In a sense, chastity could be treated as an indicator of just how obsessed a religion is with sex. The more a religion emphasizes chastity, the more they are effectively talking about and referencing sexuality. It's not just the religion that's obsessed with sex, but the adherents as well. After all, if the people themselves weren't constantly going "too far" in sexual behavior, religious leaders wouldn't have to constantly keep telling them to stop. You can't have chastity without sex.
Christian theology is filled with men who are obsessed with sex and women. Augustine himself, the author of the above quote, wrote a great deal about the need for chastity and sexual abstinence and this was arguably because he himself was obsessed with sex. He thought constantly about lust and then hated himself for impure thoughts then went back to lust in a constant cycle. He had a concubine he abandoned when his mother arranged a society marriage for him — but his fiancee was under age and he couldn't wait two years, so he entered a relationship with another woman. That supposedly led to his above prayer.
We can see similar dynamics in other aspects of Christianity, though they tend to be connected to sex. Christians who are most vociferous in their denunciations of homosexuality seem to be obsessed with gay sex — and too often, it turns out they happen to be gay as well, but just in denial. Some Christians are vociferous in their denunciations of pornography and sex toys, but don't you wonder what they have stashed in the back of the closet at home? Wouldn't you like to see what pops up in their browser history? Well, maybe not.