Lengthy article on an abortion doctor who identifies himself as a Christian. He's under the impression that his actions are similar to that of the good Samaritan. http://www.esquire.com/features/abortion-ministry-of-dr-willie-parker-0914
I don't have a great answer, but I am fully confident that until there is significant brain development and function, it isn't a person. If a fetus were a person, it would be clinically brain dead until about 25 weeks. So let's say I believe, to be on the safe side, life begins at roughly about 25 weeks, or if tools are available when electroencephalography (EEG) activity begins.
I just don't see how anyone can put a time frame on it. It is developing and growing, just leave it alone. It might not be a functioning person yet, but it soon will be. All the cells are there, they are just not specialized yet.
Another thing ended by Willie Parker is the Seattle Seahawks' Super Bowl aspirations in Super Bowl XL [video=youtube;DcIcKdf2Exs]https://www.youtube.com/watch?v=DcIcKdf2Exs[/video]
I believe consciousness and by extension personhood/humanity is more than the sum of its parts. In the same way we couldn't arrange a collection of differentiated cells into a person in a petri dish, I do not believe the foundation being laid or the sequence of divisions possible to make a person means the same thing as an actual person. Otherwise, why would we need the words "make," or "foundation?" A house is a house, a foundation is not. I've used this analogy before, but eating a walnut or an almond is not considered the same as eating a tree. Eating a pecan pie is not seen as clearing a forest. I see no difference when looking at human tissue that is not yet thinking or emoting.