How do you explain the various Judeo-Christian positions on abortion?
Roman Catholicism & Abortion:
Roman Catholicism is popularly associated with a strict anti-abortion position, but this strictness only dates to Pope Pius XI’s 1930 encyclical Casti Connubii. Before this, there was more debate on abortion. The Bible doesn’t condemn abortion and Church tradition rarely addresses it. Early church theologians generally allow abortion in the first 3 months and prior to quickening, when the soul supposedly entered the fetus. For a long time, the Vatican refused to issue a binding position.
Protestant Christianity & Abortion:
Protestantism is perhaps one of the most diffuse and de-centralized religious traditions in the world. There is almost nothing that isn’t true of some denomination somewhere. Vocal, vociferous opposition to abortion is common in Protestant circles but support for abortion rights is also common — it’s just not as loud. There is no single Protesant position on abortion, but Protestants who oppose abortion sometimes portray themselves as the only true Christians.
Judaism & Abortion:
Ancient Judaism was naturally pro-natalist, but without a central authority dictating orthodox beliefs, there has been vigorous debate on abortion. The only scriptural mention of anything like an abortion does not treat it as murder. Jewish tradition allows for abortion for the sake of the mother because there is no soul in the first 40 days, and even in the latter stages of pregnancy, the fetus has a lower moral status than the mother. In some cases, it may even be a mitzvah, or sacred duty.
http://atheism.about.com/od/abortioncontraception/p/Religions.htm