I've got a question for you then--do you believe that abortion of viable infants should be illegal? At this time, there are abortionists who perform elective abortions at 28 weeks.
Not only do I believe that abortions at the "age of viability" should be illegal, I believe abortions should be illegal at the development of the central nervous system, which is generally agreed to be sometime in the second trimester, weeks 12 - 24.
I think drawing the line for abortions at 12 weeks is reasonable. Any later than that and the fetus may be a sentinent being...
If those who demand that Christians demonstrate scientifically when "ensoulment" occurs would be so kind as to give us evidence of the same quality they demand indicating when "personhood" is invested, then we would at least have some basis for a more productive discussion. I haven't really seen much evidence that one's arbitrary designation of personhood being a good way to determine whether or not one is entitled to the most basic of human rights--the things which are necessary for bodily survival. I've seen much historical evidence that when a designation of personhood determines said rights, the end achievement is invariably evil.
Simply put, the rights to the things necessary to bodily survival are obtained when a being is capable of an interest in bodily survival.
A fetus at 24 weeks that can be seen squirming in the womb while a physican dismembers it clearly shows this interest. At conception, the zygote does not. It is not yet capable of having interests...
I don't think sentinence is an arbitrary disctinction, we as people use it all the time.
Consider this:
-Generally speaking, killing a human is a henious crime.
-Most people will agree that killing an mammal such as dog, cat, or dolphin is henious. (animal abuse laws)
However few object to the killing simpler animal life, like insects and lobsters. (we boil lobsters alive before eating them)
Fewer still object to the killing of bacteria.
No one objects to killing plants, since we eat them...
Why is it that we can legally "put down" our dog, but it's generally much harder to "put down" a human being?
Why is it that taking a saw and cutting your cat in half would land you in jail for animal abuse, yet fishermen bisect earthworms in a similar manner all the time?
Why is it that even the most hardcore animal rights activist has no problem killing plants?
You get the point...
Sentinence is what makes people people, it is what distinguishes us from the rest of the animal kingdom.