I don't think it's a difference of opinion where KILLING is concerned. It's more like a difference of opinion about WHEN LIFE BEGINS. Apparently, some people believe that a single cell is life and it would be wrong to kill it. Others believe that a single cell is not the equivilent of a human being. Those that are anti-abortion view what is being aborted as a life. Those that are pro-choice do not view it as a life.
I'm going to presume that you know the difference between a fertilized ovum and, say, one of your skin cells, right? You're only using an extremist argument to make a point, right?
OK, so what if we don't decide a fertilized ovum is a life. What if we decide it has to multiply to 3 cells first, like that French biologist I was talking about. Or maybe we should use the 16 cell stage?
How many abortions do you know of that occur between the first and the 16th cell?
Shalom.