*sigh*...so much of this controversy is bound up in language and the way we 'load' some of our words.

The minute we (or someone we trust, like a pastor) connect the contents of a Petri dish with the concept 'potential life', the debate is colored by that linguistic linking.
   It takes real effort to ask ourselves exactly what we are referring to and what assumptions we are making by using the words that way.

As has been stated in several ways by several people, there is a very large difference between a fertilized ova in the womb and a few cells combined to form a zygote which will NOT be implanted in a womb. To view both situations with images of 'innocent lives'...i.e., babies, is to overlay biology with an arbitrary, and often personal, interpretation of the situation.
It is in some ways understandable, but perhaps not accurate.

In any case, IF we cannot agree, I say again, we need to leave the decision to those directly concerned.