Very easy to answer, Eliza, and it has nothing to do with religion: Most societies want to profit from fathers who are by nature highly motivated to foster their genetic offspring. Therefore they go / went at great length to discourage the other strategy of fathers, to maximize their offspring in number without further investment, leaving the raising to the mothers, cuckolds, and to society in general.

The masturbation obsession seems to have started only in 18th century, when the "enlightened" medical profession discovered that inmates of lunatic asylums masturbated frequently - they had no reputation to lose - and astutely concluded that masturbating causes mental illness. Ethicists quickly adopted the notion. Most dropped it again in the 20th century, but Catholics had the idea that whatever they once pronounce as God's will must remain true forever.

Similar considerations apply to homosexuality, which many people seriously believed to be caused by seduction.