FWIW, most churches I've attended view sex as a good thing: the most intimate of acts, reserved for the union of marriage. Sex is not sin, or even close to it; using it for the wrong purposes is. I don't know of anywhere in the bible where marital sex is even implied to be sinful or unhealthy (except for perhaps regarding activity during a woman's menstruation in the OT law- but there's a lot more to that than sexual activity). I realize that there are some Christians who've regarded sex as necessary only for the bearing of children, but this is VERY hard to support from the perspective of the bible. What I (and most Christians I know) come away with is that God intended sex to build/show intimacy between marital partners in a unique and special way.

As a matter of fact, I think the only places where the bible is explicit and obvious regarding sexual sin is regarding homosexuality, sex with relatives, affairs, and lust. Even the ban on pre-marital sex isn't explicit that I know of, (though I do believe it falls out naturally from the study of a marriage covenant). So for the Christian, nothing about sex is really sinful, only what we consider to be the abuse of it.