But the Bible also says,
"Judge not, that ye be not judged." - Matthew 7:1
Isn't taking someone's life away the ultimate of judgments?
That's in reference to the lay person. The Bible specifically sets up the idea that there should be professional judges.
Also, the bible states that abortion is a crime, but it is only punishable such that, "the one responsible shall be fined according as the woman's husband may exact from him, the payment to be based on reckoning." (Sometimes "reckoning" is translated to, "as the judges determine.") Exodus 21:22
It also should be noted that the verses just before this say that the if someone kills a slave (property in those days, mind you) that, "he must be avenged."
So, Exodus 21 places the value of a foetus' life below a slave's. In fact, kidnapping, striking your parent, and not preventing your ox from goring people when you know it has the propensity for such are all punishable by death; that is, they are all worse than aborting a foetus.
Furthermore, a Christian can believe whatever he or she bloody well chooses, but it may prevent him or her from being a "good Christian."