Not really. America was created based on christian principles, but the funny thing about that is that christian principles include peace and kindness. We don't mind if other people exercise knowledge based on other religions within other general area. We can't escape it, so we put up with it, as long as it does us no harm. Hence the separation of church and state: legally, we believe your beliefs should play no part in your participation in the government of this nation.

Thing is, as we let people with different principles within our nation, they begin to change the understandings of our people. That's the way it works for any system of beliefs. Religion has a bleeding effect. So ultimately, no Christian nation here on earth will ever last forever. In fact, we're such a nation so open to ideas, I imagine we'd only last a few centuries before we're knocked out...

Anyway, why do nations need religions? Like I said before, it's within my understanding that religion and unprovable beliefs form the foundation of human intelligence. In order to understand the world, different people will come up with different answers to these three core questions of our existance:

1. Where have we come from?
2. What has gone wrong?
3. How can we fix the problem?

After answering these questions, the people will then hypothesize, theorize, and generally develop ideas that answer other questions of their existance, such as:

1. What is good?
2. What is evil?
3. What is love?
4. What is hate?

And so on. Actually, those previous questions are usually answered subconsciously when we are very young, as our parents raise us. But anyway, we eventually we begin to develop less philosophical ideas and answer questions like:

1. Survival?
2. Economics?
3. Government?
4. Astonomy?
5. Technology?
6. Biology?
7. Chemisty?
8. Genetics?

And we end up with what's called a worldview, the "perspective" of our understanding, the limit of our knowledge. As humans, we all develop rational thinking. So our differences in thinking, then, are just the result of either two things: misunderstandings, or a clear difference of opinion on certain key questions that we are all naturally born with.

Well. There are obviously differences of opinion, then. And what that means (and what history shows us) is that people with similar views and understandings will tend to flock together and form coalitions, or nations, together. So those nations are ultimately built on... religion! Thus proving my point that all nations are built on core principles and beliefs.

This is a bit of a tangent, but if that's what a nation is, what is war? Pure stupidity? Not at all. It's a violent conflict based on unproveable human hypotheses regarding the core questions of our existance. Some stupidity and ineptitude has definitely played a role in the past (the Mexican War comes to my mind). But generally speaking wars are caused by something much bigger than just petty misunderstandings or a lack of intelligence.

The funny thing about human intelligence, is that if we have "core questions," where did those core questions come from? Heck, where did our intelligence come from? Why are we here, and how is it that we are asking, "Why are we here?"