Do Kingdom principles work?

I just read an article on the illogical principles of the Kingdom of God. Where the world says, do unto others as they've done unto you. The Kingdom says do unto others as you would have them do unto you. Where the world says an eye for an eye, the Kingdom says turn the other cheek. To be first in this world, you camp out overnight or get there as early as possible. In the Kingdom, to be first you are last.
That got me thinking. Often in a conversation about being peacemakers or any other Kingdom principle, someone will say, "that's what the Bible says, but we live in the world. This won't work for America. We can't expect America to behave this way." To a point, I agree. The Kingdom can only be lived out by the power of the Holy Spirit. But often, this statement is used as a defense for voting a certain way which may be in opposition to Kingdom thinking. We believe the bit about peacemaking and turning the other cheek, helping the poor but America can't be expected to live up to this standard. Somehow what we believe and what we live out seems to contradict.
If we as Christians don't believe the principles of the Kingdom will work in this world, how can we tell the world sincerely that the Kingdom of God is what we were created for? I've been accused of being an idealist. I hold the Kingdom of God up and say this is the goal. I know we are a work in progress--we are going on to perfection. But if we are not holding up the Kingdom, we are holding up the ideals of the Democrats or Republicans or Independents or America. Have we settled for lesser gods and lesser things? If we don't hold up the Kingdom's principles and values, who will?