Doctrine: If the baby is alive, don't kill it. The fact that science has been better able to determine when it is alive hasn't changed the doctrine. I think you look to the wrong sources, so that you can weaken your faith so that you can maintain your political views. Set aside your political views for a second, and start looking at things fresh.
I actually can't relate at all to your watered down Christianity that is subordinate to your politics. Perhaps for the rest of the discussion, we should just assume that God does not exist. Even secular humanists are against killing. If there is no god, then human life is the greatest thing there is. We should preserve it at the expense of all other things.
My view is consistent with Libertarians for Life. From the Wikipedia page:
1) Human offspring are human beings, persons from fertilization.
2) Abortion is homicide – the killing of one person by another.
3) There is never a right to kill an innocent person. Prenatally, we are all innocent persons.
4) A prenatal child has the right to be in the mother's body. Parents have no right to evict their children from the crib or from the womb and let them die. Instead both parents, the father as well as the mother, owe them support and protection from harm.
5) No government, nor any individual, has a just power to legally "de-person" any one of us, born or preborn.
6) The proper purpose of the law is to side with the innocent, not against them.
None of the arguments are based upon religious belief, and are intended to appeal equally to atheists and theists.
You mention rape. First, let's deal with the majority of abortions, which are purely elective. I posted this elsewhere, but you have not answered, so I will post it here: Probably the least justification for an abortive homicide would be if 2 people decide to have consensual, conjugal sex, to completion, without protection...just because they want to do it. They intentionally engage in acts that make it possible, and maybe even probable, that they create a human being. The question then becomes: Are they allowed to kill that human being? No rape, no incest, no down syndrome kid...they just decide they regret the occurrence of them becoming pregnant. If we are looking to culpability or responsibility of the parent to justify the homicide, then that case is probably the weakest case for justification. In that case, do you, Tyrone, think that abortion should be allowed? If you do, then we don't have to discuss special cases, because you believe it should be allowed in all cases.
Link: https://en.wikipedia.org/wiki/Libertarians_for_Life