This is a serious post and I will accept only serious responses. If you post anything derogatory, offensive, or just parrot partisan talking points, I will delete it.
"Would you lie to the Nazis if they asked you if you were hiding Jews?"
This common ethical case study presents a false dilemma. The answer is neither that betraying the innocent is right nor that lying is right. Both are wrong, but one is more wrong than the other. Similarly, both the ending of an innocent human life and impeding a human's bodily autonomy are wrong, but one may be more wrong than the other.
Abortion presents a particularly compelling case, as preserving the bodily autonomy of one necessitates ending the life and violating the bodily autonomy of the other. Therefore, terminating a pregnancy can be wrong, but continuing the pregnancy can also be wrong. Failure to terminate a pregnancy when the mother so desires is wrong because it impedes her bodily autonomy--this is particularly true in the case of rape, as forcible continuation of a pregnancy is the forcible continuation of a crime. On the other hand, if the mother desires to continue the pregnancy, there is no moral dilemma.
To make an ethical judgement regarding which is more wrong, we need to determine the point at which the mother's bodily autonomy trumps the life and bodily autonomy of the fetus--and it is not the same point in every pregnancy. Obviously, once the child is born the mother's bodily autonomy is no longer at risk, and therefore no longer a consideration. Similarly obviously, prior to conception there is no separate human life and no bodily autonomy on which to impede, so the life and bodily autonomy of the zygote are not a consideration.
I argue that, as a pregnancy progresses, the value of the fetus' life and bodily autonomy gradually increases, and the mother's bodily autonomy gradually decreases. Unless one wishes to completely discount the mother's bodily autonomy entirely (as is found on the political far right), one cannot argue that the mother's bodily autonomy carries zero weight in the moral calculus from the moment of conception. Unless one wishes to completely discount the fetus' life and bodily autonomy entirely (as is found on the political far left), one cannot argue that the fetus' life and bodily autonomy carries zero weight in the moral calculus until the moment after birth. (Regarding the latter conception, I also argue that the moral repugnance with which most people hold partial-birth abortion--particularly if they have witnessed it--demonstrates that, despite what we may believe politically, our consciences testify that this is wrong.)
Consequently, when making a moral judgement on abortion, the state of the pregnancy, i.e., the developmental stage of the fetus, must be measured against the harm done to the mother. To a certain extent, our laws have accommodated this distinction. The restrictions on late-term abortions demonstrate that increasing weight is given to the fetus' moral standing. The typical exceptions for rape, incest, and medical necessity demonstrate that increased weight is also given to the burden on the mother. However, and this is the last great caveat, there is not a 1:1 correspondence between that which is moral and that which is legal. The interests of the state may exceed, or more likely fall short of, our moral judgement. (I have previously blogged about the limits of the state's interest in abortion
Also, moral concerns and spiritual concerns are not necessarily the same thing. As a Christian who believes that all people are made in the image of God with immortal souls, I grieve whenever a life is cut off without access to Baptism or the Gospel. I believe that God is a merciful God, that He will not cut any off from grace who may believe, and that He may have a means to save those whose lives were ended in the womb, but I cannot be sure. Abortion may be the least wrong choice we can make in our sin-cursed world, but that doesn't make it right.