This article brings out why abortion is ultimately a religious issue. If you are not convinced that human life itself is sacred, and made in the image of God, than the grotesque nature of the procedure be no more significant than, as someone said above, dressing a deer carcus.
This is why the issue has to be the fact that humans are made in God's image and deserve to be treated with respect and dignity--as human life is especially sacred. The argument cannot be simply that abortion kills human life--because ultimately those behind abortion, shrug their shoulders and say, "so what?"
This issue perfectly illustrates what happens when the separation of church and state becomes radical--and religion is relegated to the realm of personal emotions--irrelevant to political issues. Religiously informed opinions are every bit as valid and more, as those from mere secular sources--and deserve, indeed need, a place at the table of political discourse.
I am going to have to disagree with you. Abortion is a moral issue, but not a religious issue. Atheists can know that abortion is wrong, as some do, just like they know stealing is wrong.