I'm 100% pro-life -- even conscious animal life, should be respected to the highest degree possible. However, an unfertilized embryo is not yet a life in a moral sense because it has never been conscious, and does not become conscious until some later point during development. Otherwise, then millions of people are dying merely by the fact that about a third of embryos naturally fail to implant, and this is a crisis that requires immediate intervention. At an earlier stage of pregnancy, the life of people who are or have been conscious, and will be again, has to be given a higher priority.
A ban on abortion after the point of fetal first consciousness does make sense, but I understand people who would oppose it even then, on the ground that no person is obligated to lend the use of their body to another, even if it would result in the other's death. I wouldn't support that position, but I think it's the one a strict libertarian would take.
As far as the Bible goes, it is does not
unambiguously take the modern anti-abortion rights stance by any means. Indeed, both St. Augustine and Thomas Aquinas both cited "quickening" as the point of "ensoulment", and in this respect I think my position outlined above is closer to theirs, than the view that a fully moral human is created at the moment the sperm penetrates the egg.
