Like I've pointed out before, any time you involve religion in the law, it's an absolute mess. That's because laws are all about equity, and religions all have their own ideas about what is right and proper. It says right in our constitution that the government can't favor any religion over another. So the only legal thing to do is for the government to ignore them all (since it's impossible to make the law agree with them all). But this Supreme Court seems intent on breaking as much as possible.
That "First Breath" meme was Catholic dogma for many centuries, as their theologians believed the soul entered the body at the first breath. Personally, I like the belief of some Jewish groups these days that abortion should be permitted until the fetus graduates from medical or law school.
