Some people even within the Christian community do not want abortion to be made illegal because they hold to the mindset that regardless of the law, a person determined to get an abortion will still find a way. And thus, they are concerned that this would lead to more risk to the mother, with possible lasting complications, and that female mortality rates are going to go up if abortions were to be carried out underground. So why should abortion be made illegal considering all this?
(P.S. I am working on a blog and looking to answer this question. Thus, your reply to this answer might be used by me if appropriate. Thank you!)
I find this question very difficult. (Full disclosure: I was once radically pro-choice, have multiple friends who have had abortions, one of whom I supported through it. I spent a bit of time in law school involved in reproductive rights issues, was at one point crafting a pro-choice legal argument, and then when I converted, the impossible happened and I decided that abortion was in fact immoral and in certain circumstances murder. I now oppose the extremism of the pro-choice movement, but I know too much about the issue from both sides now to think it's an easy one.)
Why should abortion not be illegal? Frankly, in part because I still do not trust the pro-life movement. Those who champion reproductive rights internationally focus in part on some of the problems happening in Latin America, where anti-abortion measures are so draconian that women in poverty with no access to healthcare who miscarry are often imprisoned on false charges of abortion. Why? Because there's the lingering, misogynistic (and classist) suspicion in these cases that she did it on purpose, and doctors are turning women in who seek emergency help. Pregnancy is not a simple thing--it actually is a complicated medical situation and needs to be treated like one.
I do not support abortion on demand up until birth. I would get behind something like a 20 week ban (or possibly even 12 week, Ireland style), if it were well crafted, didn't penalize women for seeking medical attention, and left emergency situations to the discretion of the doctors. I would also be behind a German style solution, where abortion is illegal on the books because of the sanctity of life, but in practice tolerated in the first trimester. I think more needs to be done to fight selective abortion (sex selection, intersex or Down Syndrome), and that there needs to be some sort of genuine moral reawakening to shut down the "shout out my abortion" crowd, since what's going on there is pure dehumanization, but at the same time, the early stages of pregnancy are so precarious for the embryo in the first place that I don't think a secular government has a compelling justification for prioritizing it over the woman. That doesn't mean it's morally correct to abort, since I don't think it is, but I would like to see more of a focus on expanding women's healthcare and fighting poverty.