There is one question that makes or breaks the entire abortion issue for both sides. What kind of being is it? The answer one gives is pivotal, the deciding element that trumps all other considerations. All arguments are either made irrelevant (if it is not a human person) or insufficient (if it is a human person). All the arguments reduce to this issue and either find their grounding or their nullification here. This argument was brought to my attention through a podcast that I cannot recommend highly enough (link below).
"Let me put the issue plainly. If the unborn is not a human person, no justification for abortion is necessary. However, if the unborn is a human person, no justification for abortion is adequate."
- Greg Koukl, founder of Stand To Reason Ministries
This argument may seem too simplistic to some, but I would suggest that it seems this way because we have made the issue too complicated. Arguments are presented regarding the health of the fetus, the relationship between the parents (i.e. rape, incest) and the rights of the mother. However, while these arguments do have issues that must be dealt with, they are secondary if the fetus in question is a person.
Every person's response should be obvious. No matter what side of the argument you fall on, there seems to be a clear burden on every person to answer this question. Any one who votes, who has any impact on public policy, should feel obligated to research enough to know whether or not a fetus is a human being.
http://www.str.org/