Civitas contra religionem

So many people laud the founding fathers' decision to establish a policy of separation of Church and state. But I have to ask: is this really the best thing for us?
A lot of the argument for the separation of Church and state lies in the fact that with a government tied with a church, there will be no freedom of religion. We have plenty of examples in the history of the world to draw from: England, Rome, Germany, France, Saudi Arabia, Israel, Lebanon, Iran, etc. Some countries have failed to allow religious diversity, but not all. England no longer does. Israel and Lebanon have always allowed religious freedom. None of these countries are considered disasters (though, to be fair, none of them are really driven by the Church anymore).
So what does separation do for us here in the states? First and foremost, anybody can join whatever faith they'd like, for better or worse (viz Heaven's Gate, David Koresh and Jim Jones). Furthermore, politics supposedly isn't influenced by religions (like Hell it's not). But if politics is supposed to be fair, and representative, why is it that the most dominant Christian religion in America (the Catholic Church) has only ever had one of its members become president?
But what I really get upset about is this: American Christianity is so often influenced by the state. What does this mean? How many churches today in America are predominantly war-like? How many good Christians are afraid to protest what they think is unjust? How many Christians view the Beattitudes as a higher standard than political practice? How many consider the command to love one's neighbor more important than the constitution? How many people consider Jesus to be a more important political figure than George Washington?
The problem is that we live in a world affected by World War I nationalism that we have never overcome. Christians, in word, proclaim a life that is independent of the state. Jesus proclaimed "My kingdom is not of this world." The early Christians suffered at the hands of the state, often to imprisonment and even death.
Now, we live in Kierkegaard's Christendom. We don't actually need to be Christ-like in order to be Christians in our world. We go to war, we impose taxes on the poor and increase the wealth of the poor. We turn against our neighbor and engage in unvirtuous enterprises. Christianity in America is like a new Rome. We have lost our sense of Christianity for our sense of politics. We worship the God of the state, the God whose name is printed on our money, not the God of Christianity.