Having started with what promises to be an incredibly controversial topic I hope to disappoint by beginning and concluding with non-controversial points (who knows what might happen in between). My foundational assumption is that as Christians we are called to agape (originally translated as "charity" then as "love") for our neighbors. I believe that our neighbors are anyone and everyone we meet or become aware of who happens to need agape (which is pretty much everyone). I understand agape to be genuine care for someones well being even and above our own well being. If this is as non-controversial as I think it is, let's move on.
I have become aware, over the last several years, that people of good political will claim to be motivated by a love for society or for their country or culture. Because this good will towards society tends to be more evident in one political party than in others at a given time, Christians tend to feel a certain pressure to identify with whichever party that is. Those who choose to identify with other parties usually defend their participation as wisdom seeing through platforms which "claim to help but will ultimately hurt". I do not want to fault the motives of either group of Christians. I believe agape should always be encouraged as a motivation both in political and private spheres. What I think is rather tragically missing on both sides is an awareness of the second half of our calling. We are to have agape for our neighbors. Contrast this with having agape for society.
Neighbors are always individuals, society is not. Society is bigger than individuals but it is less important; that is, society is only as important as the individuals of whom it is constructed. The worth, the value of society comes from the individuals (the neighbors) which are it's constituents. It is worth noticing what the effects of valuing society over the neighbor are. If society is our primary focus then we must be willing to "break a few eggs" to make our "omelet". Put another way, if society is more important than the neighbor then we might have to sacrifice the occasional neighbor for the good of society. I think that most people and nearly all politicians take this for granted.
But if we turn the focus around, something truly beautiful emerges. If we focus on having agape for each and every neighbor we run across or become aware of, we must ultimately benefit society since society is made up exclusively of neighbors. Thus if we prioritize society over the neighbor we fail to show agape to at least some neighbors. In fact I suspect that we will fail to have agape for society as well since it is impossible to value an abstract (society) over a concrete (ourselves and our neighbors). If, instead, we prioritize our neighbor over society, we will end up having agape for each and every part of society we encounter. C.S. Lewis called this the "law of first and second things". He pointed out that when we put first things first we nearly always get the second things as well. but when we try to put second things first we end up with neither first or second things.
So what is my conclusion? I think the implication here is not that Christians shouldn't be involved in civil government, or that we need to avoid associating with any particular party. What I do think is that we should be incredibly careful when it comes to supporting any law which admits to breaking "a few eggs". Christians are and ought to be many things but we can never be utilitarians.