Haven't read the rest the previous discussion but...
of course there are good evidence based reasons for abstinence. The problem is that these are not the reasons that religions use. The reason they use is that "god says so".
If the reasons were known, instead of divine edicts, we could modify our moral positions when conditions change. For instance, today there is no reason any woman who does not wish too should get pregnant. We have extrememly effective birth control these days -- a very recent development. Our religious morals have not caught up .
In a very backwards form of reasoning, many religions now say that birth control is immoral.... only because it would invalidate the moral rules that they have internalized without question for so long.
summary: of course most "moral values" have reasonable evidence based rationales. The problem comes when we do not understand that these are real reasons, and instead attribute the moral rules it some absolute rigid moral standard.