I hear what you are saying, Egan. And I agree in many ways. I would like to see more non-religious arguments used in the abortion debate, on both sides. This is not a clear-cut religious-non religious argument. There are pro-choice Christians.

To me, the simple fact is that a new human being comes into existence at conception.That is a scientific fact. To terminate the life of that human being at any point afterwards is done on the basis of a subjective belief system. Those who kill the developing human being do so on the basis of their belief it is not a valid human life. They disagree over when it is a valid life. Some say three months, others at the point when the baby can survive outside the womb. They kill on the basis of their belief that a certain thing makes us who we are. For atheists, this is often sentience. For those who believe we have a soul, it's at the time they believe the baby gets a soul, which can vary from implantation, to sentience, to actual first breath outside the womb.

All those things are subjective opinion. The only science in the issue is the fact is that a new human being exists from conception who will go through all the normal stage of human development (fetus, baby, child, teenager, adult) unless someone kills it, it gets sick, or dies some way else.

Abortion is the prime example of how a belief system is justified to kill. Science is totally ignored in favour of individual beliefs, profit, and convenience. Those who support abortion can't very well condemn others who make decisions about their children's lives based on a belief system i.e. circumcision or spanking because they are prepared to kill on the conviction that they are right.