Garry Wills, in the NYT (July 27, 2004):

Catholic bishops recently met and sought the best way to enforce" church teaching" with Catholic politicians who fail to oppose laws that allow abortion. Some critics of the bishops see this as a violation of the separation of church and state. Both sides are working from misconceptions. Abortion is not a church issue, so what the bishops have to say about it cannot be an intrusion of the church into state concerns. Abortion is, admittedly, a moral issue — but not one that can be settled by theology or by religious authority.

Modern"right to life" issues — abortion and contraception — are nowhere mentioned in either Jewish or Christian Scripture. Pope Pius XI said they were, in his encyclical Casti Connubii (1930), where Onan's"spilling his seed on the ground" (and the reason for his punishment by God) was interpreted as preventing conception and birth. Yet no scholar of Scripture accepts that reading of Genesis 38:9 anymore; it is read as referring to levirate marriage duties. The Vatican now agrees with this interpretation. Even in his own sphere, the revealed word of God, the pope could be wrong.

Some, deprived of the Onan text, say that abortion is forbidden by the scriptural commandment"Thou shalt not kill." But that commandment does not cover all human life. My hair and fingernails, while growing, are alive with my own human life. Semen and ova have human life even before their juncture. They continue to have it after mingling — for example, the fertilized ovum that does not lodge itself in the wall of the womb. Yet no attempt is made to retrieve such"dead" detritus and give it decent burial.

So"right to life" as a slogan is a question-begging term. The command not to kill is directed at the killing of persons, and the issue in abortion is this: When does the fetus become a person? The answer to that is not given by church teaching. Even St. Thomas Aquinas, who thought that a soul was infused into the body, could only guess when that infusion took place (and he did not guess"at fertilization"). St. Augustine confessed an agnosticism about the human status of the fetus.