(Denny Crane: "I Don't Want To Socialize With A Pinko Liberal Democrat Commie. Say What You Like About Republicans. We Stick To Our Convictions. Even When We Know We're Dead Wrong.")
The reason why it isn't in the same ballpark is that the pro-life position is in accordance with Christianity, but does not naturally follow from any belief system which ascribes divine inspiration to the Old Testament and not to the New Testament.
CHAPTER XLVOF DEMONOLOGY AND OTHER RELICS OF THE RELIGION OF THE GENTILES
The Israelites, when they worshipped the calf, did think they worshipped the God that brought them out of Egypt, and yet it was idolatry, because they thought the calf either was that God, or had Him in his belly. And though some man may think it impossible for people to be so stupid as to think the image to be God, or a saint, or to worship it in that notion, yet it is manifest in Scripture to the contrary; where, when the golden calf was made, the people said, "These are thy gods, O Israel";[Exodus, 32] and where the images of Laban are called his gods. [Genesis, 31. 30] And we see daily by experience in all sorts of people that such men as study nothing but their food and ease are content to believe any absurdity, rather than to trouble themselves to examine it, holding their faith as it were by entail unalienable, except by an express and new law...
But what commandments are those that God hath given us? Are all those laws which were given to the Jews by the hand of Moses the commandments of God? If they be, why are not Christians taught to obey them? If they be not, what others are so, besides the law of nature? For our Christ hath not given us new laws, but counsel to observe those we are subject to; that is to say, the laws of nature, and the laws of our several sovereigns: nor did he make any new law to the Jews in his Sermon on the Mount, but only expounded the laws of Moses, to which they were subject before. The laws of God therefore are none but the laws of nature, whereof the principal is that we should not violate our faith...
http://oregonstate.edu/instruct/phl302/texts/hobbes/leviathan-j.html#CHAPTER%20XLIV
I am Jewish but I do feel differently than the rabbis who decreed that a person doesn't have a soul until he takes a first breath. I feel that indeed we know more about the unborn than we did at that time, and that ultrasound machines do show quite the living human in there. The ancient rabbis, blessed they may be, could not see the babies in there. I know they would have known the truth had they had an ultrasound machine. They would never have condoned abortion as not a murder.