IMO the process of the development of life begins at conception and ends at death. Anywhere in between, one shouldn't have the legal right to disturb that via killing. Sadly, there are events such as wars that get in the way of the ideal. However, as a total, no being has the right to determine whether a fellow being can live or not.
This more or less is where I stand on it. The same reason I oppose the death penalty is the exact reason I oppose abortion. I feel my right to life from when I was just conceived to when I was about to come out of my mother's womb to if I'm ever serving life in jail should be protected.
And I'm an atheist(If that's even relevant)