99% percent of people who support abortion are not evil. They simply have framed the problem wrong in their heads. They see it as a women's rights issue. This is why most debates on the topic go nowhere; the two sides are having completely different discussions.
What got me to really reconsider was someone who asked if it would be ok to kill a baby born 4 months premature. At first I thought, "sure, that'd be silly. But there is a limit to how premature a baby can be born and still survive, so THAT should be the cutoff for abortion". Then I realized that with advances in science and medicine, that cutoff point would be continuously pushed back. That realization showed me that my logic was flawed. I'm still not 100% "pro life"; I think the safety of the mother should be taken into consideration (though this is quite rare these days. It happens, but it's rare), and I also think 1st trimester abortions should be legal, simply to avoid the black marketization of the procedure.
I also know that when I mentioned this change of heart to my female friends (in NYC, mind you) they were quite unhappy with me.