If you're running over someone's conscience on a matter involving human life and death, why do you care that their conscience is based on religion?

Personally, if someone is morally opposed to what they perceive as killing, I don't care if their morals are based on religion, atheism, or just squeamishness. Preserve their moral objection to killing. It's too valuable to society for us to trample on it.

I am also not religious (and generally agnostic about the so-called supernatural), but it seems pretty obvious to me why religious beliefs play a major role in the debate over abortion. It all comes down to my favorite subject: the Explanatory Gap.

Setting aside arguments that abortion is permissible even if the fetus has a right to life (e.g. Thomson's "A Defense of Abortion"), for many people the crux of the matter is whether or not a fetus is a living human being. The problem is that current science cannot tell us exactly when a clump of cells becomes conscious; we don't fully understand consciousness, so assigning it to a given object can be contentious. We simply have no good way of knowing when there is a person "in there", so to speak.

Since science cannot answer this question, religion has filled the void with beliefs about when someone's life actually begins. If we understood consciousness and could detect when it "starts", I suspect this debate would be much less dramatic.