The First Amendment to the U.S. Constitution begins, "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof."
The wording is clear and not the least bit ambiguous. The United States is a secular state, and religion is a personal matter, which a person is free to express as they see fit. Freedom of religion, of course, includes freedom from religion.
Yet despite this obvious separation of religion and state in the Constitution, there are those in the Christian Right who want the U.S. to become a theocratic state that embodies their particular religious ideas into law. Nothing could be more un-American, for religious freedom flourishes when no particular religion is embraced by the state. After all, religious belief is all a matter of opinion. That's why there is a multiplicity of religions and a multiplicity of interpretations of every religion.
While there are those who claim that religious belief is the basis of morality, human experience shows otherwise, for religious belief and ethical conduct are two different things. Moral behavior need not be based on some religious doctrine or fear of a punishing God if one does wrong, but simply treating others as we would want to be treated. God doesn't enter into such an equation, and it doesn't matter. Thus, two of the most honest and ethical people I know are one friend who is an atheist and another who is an agnostic.
On the other hand, wars, inquisitions, discrimination, repression and other evil behavior has been caused by those who have tried to impose their religious beliefs on others. It has been estimated that more people have been killed in the name of religion than any other cause. In passing the First Amendment, the Founding Fathers were well aware of Europe's bloody history of religious wars and didn't want to see the same on American soil.
Today, we can see theocratic states such as Saudi Arabia and Iran, along with movements such as the Taliban. They are backward and repressive, with no real notions of democracy and freedom of speech, persecute religious dissenters and treat women abominably. Much of their authoritarian mindset can be seen in the Christian Right. Religion has its place for some people, but guiding public policy is none of its business.