To Promise With

That's what the Latin etymological meaning of compromise is, "to promise with". Of course we know that it means agreeing to give up or 'flex' on something you value to get something else you value in the bargain. Politicians trading off on aspects of a piece of legislation is probably one of the more common examples. Arduous http://arduousblog.blogspot.com/ wrote an excellent post about compromising some of her green values for the sake of good relationships.
I have been in a discussion with Shawn on his Tribe site http://www.lofitribe.com/ about voting. Here's the jist of it. He has decided in a very Anabaptist-traditional way, to not vote in the presidential(and I assume any other) election, because none of the candidates will govern according to "Kingdom principles". When pressed as to who decided what those principles are and how they would be applied, he stated that they are clearly presented in "Matthew 5ff" in a manner that does not allow for compromise. His reference to the Sermon On The Mount includes the injunction to "pluck out your eye if it offends thee", that is if you look lustfully at another person. Is that mere Hebraic hyperbole, or was Jesus giving a serious command? Who decides? Shawn hasn't addressed that yet, I don't think he will. My question was and is, if you can't find perfection is it appropriate to withdraw from responsibilities?
For example, if Arduous went to her mother's house and her mom purchased all non-local food to prepare dinner, is it appropriate for Arduous to refuse to eat, thereby abnegating her responsibility to honor her mother? If I can't find organically grown veggies at market, do I quit eating veggies, tossing aside my personal responsibilty to strive for healthy eating habits?
I remember reading about, and even speaking to, people who didn't like Bush, but they also didn't like Kerry-so they didn't vote at all. See where THAT got us!
Of course these are not examples of choices that compromise perceived religious principle, but when religious principle and civic responsibility seem to be at odds, what does one do? Note I am not simply saying obedience to law; the Anabaptists were right to violate the prohibitions against adult baptism and preaching beliefs that differed from the state church. These were strictly religious matters and subject to 'higher authority' as the saying goes.
But do Jehovah's Witnesses have the right to withhold potentially lifesaving blood transfusions from their children because of religious beliefs? Do we have a responsibility as citizens to vote, even if it seems to clash with some religious vision of the way things oughta be?
How much compromise is acceptable? Where would you draw the line in the dirt?
If you are interested in a stark but beautiful portrayal of this question lived out, read Silence by Shusako Endo.