Interesting question. I suspect that the anti-abortion movement is not philosophically monolithic enough to give a single answer. Just to look at one of the more radical fringes with which I am somewhat familiar, the Christian Reconstructionists by and large reject the idea of armed rebellion against the state, on the grounds that this violates God’s law (see Romans 13:1). They therefore seek the gradual replacement of our secular legal system with a Blblical law order in which abortion (among many other things) would be punishable by death, applicable to both doctors who perform abortions and mothers who have them.
I don’t entirely trust the CR’s about that “gradual” and “non-violent” bit–they also have something called the “doctrine of the lesser magistrate”, which holds that citizens have a right to armed resistance if they are under the authority of a subordinate level of government; i.e., the duly constituted authorities of a state or even local government could lead a lawful resistance against the national government if the national government violates God’s laws.
There are a handful of Christian Reconstructionist lesser magistrates–city councilmen and state legislators and so forth–but so far none has sought to lead the Christian resistance against the evil baby-killing Leviathan federal government. In prudential terms, they’d get slaughtered and they no doubt know it–we’re talking about some selectman from suburban Cleveland teaming up with an Ohio state assemblyman to lead maybe a few dozen people against the armed forces of a superpower, with about zero support from the public at large.
Bear in mind that Nazi Germany didn’t really experience as much internal armed resistance as you might think; what armed resistance it did encounter was mainly in foreign countries overrun and occupied in war, not in Germany itself, where the Nazis had come to power by quasi-legitimate means; and Nazi Germany was at war with foreign enemies who actively sought to aid local resistance groups. The Recons know perfectly well that their situation is nothing like that of the Underground in World War II in that sense; i.e., no sense by the general populace that the government is an invading and occupying force, and no powerful external allies to provide aid and comfort (not to mention to eventually win the war by sheer military force–it’s not like France was actually liberated by the Underground).
Even if you buy the extreme right’s fantastic rhetoric about the evils of the U.S. government, the situation would be more analogous to the post-WWII Soviet Union, where armed resistance was largely nonexistant and opposition to the regime was confined mainly to peaceful dissidents.
