Abortion..?

I'm just wondering about abortion and I'm not pregnant or anything...! I understand that some people have religious beliefs dictating their views on abortion, and that's fine but- I don't really get why it's so wrong. To me, a foetus is just 2 cells dividing by meiosis and, afterall, if a woman has an abortion because she absolutely cannot afford to bring up a child, isn't that a good thing? The child wouldn't have had such a good quality of life. Anyway, a vast amount of the world's problems stem from the fact that the world is simply over populated by humans. I suppose what I'm trying to say is; are religious views the reason why people think abortion is wrong? Or is there more to it?