And, while you're at it, please answer my original question rather than throwing out strawman arguments.
> why should my employer get to decide whether I'm opted in or out of a particular thing based on religion?
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.
Not when pro life means human life begins at conception.