The main point to Pro-life arguments is that God believes "life" begins with conception. So if we all have the "right" to choose our own religious beliefs, why is it that so many people think they have a right to control a woman's reproductive choice ? Doesn't this all come down to a conflict of church (religion) and state (rights) ??
I am pro-choice, but only to the extent that having an abortion never becomes as casual as some ardent privacy rights "zealots" seem to want to make it. I happen to believe that what is created within a woman's body when she becomes pregnant does represent a form of life. Imagine all of the preparations that happily pregnant women undertake to make sure that whatever that is is safe throughout the pregnancy. And does a happily pregnant woman refer to her unborn as matter, an embryo, a fetus, a zygote or any other such scientifically and socially ambiguous term? No, of course not. She talks to her unborn "baby." She reads her "baby" stories. She personifies every kick and every repositioning. She makes reference to "eating for two." I believe that pregnant woman are carrying life. Therefore, while there are definitely circumstances where it would be inappropriate or unhealthy to bring that life to term, those are rare and extreme and should never become casual.
Finally, I do not believe that, in general, men should tell women what to do with their bodies. I do not believe that two unmarried persons have an equal say to what happens to the baby that the woman is unexpectedly, and perhaps unhappily carrying. I do, however, happen to believe that two people in a healthy monogamous relationship (which is intended to be long-term) should have a series of serious dialogs when a baby unexpectedly manifests itself. The ultimate choice is hers, but she should consider his reasonable feelings when making this crucial decision.
This is a right that must be protected at all costs, but not exploited as a casual life event. Education, abstinence, contraception, and adoption are all measures that can be taken (and should be considered) to greatly reduce the occasions where abortion becomes the ultimate answer.
This discussion of rights isn't generally had in the context of a discourse on separation of church and state (primarily because those discourses, under the First Amendment Establishment Clause, require the State not to endorse or support any particular religion. The State can, however, endorse the ideal of faith and of being religious generally, which many view as positive for society's morality. I happen to believe that even this much State involvement is dangerous.
Please consider this my respectfully-presented, respectfully-intended personal viewpoint.