Imperial;
You make a very valid point, but the difference in that example is that they are dealing with dead people. Pro-lifers believe that aborting a fetus constitutes murder. Therefore, they believe that they are fighting against the murdering of innocent babies. Telling them to stop "forcing their beliefs" on others is basically telling them to condone what they feel is the murder of human beings whose only crime was living. To further play devil's advocate, a pro-lifer could possibly make the argument that people who support abortion but oppose, say, the Iraq war are hypocrites, because while they are against the deaths of innocent civilians, they aren't against the deaths of innocent babies. Of course, it's not quite that simple, but there are a few valid comparisons.
It's just a tricky subject. Personally, I'm pro-choice as long as it's not just some idiot girl getting pregnant every other month because she won't take the initiative to use contraception. Personally, I think that abortions should only be legal in standardized facilities, and cost hundreds of dollars to have performed, unless it is a life-or-death situation for the mother, or stemming from rape, incest, etc. That would discourage their use as a way for couples to have unprotected sex and not have to worry about getting pregnant. I know a slutty bint who's had five abortions since she was 16. They're easy to schedule, and they didn't cost her any money, so she doesn't see why she needs to be careful... it's ridiculous.
People just aren't careful enough with sex. I don't have sex with any girlfriend unless she's on a pill/shot/rod/etc., and even then, I use a physical barrier. While I don't necessarily oppose abortion, I would rather we minimize the number of fetuses that have to be aborted. The fewer lives that are frivolously ended, the better.
