According to a book on American theocracy, fundamentalistism has been a strong feature of American belief since Plymouth Rock. I had to read the book quickly but America has always had its high share of relgious crazies. A lot depends on where you live. Fundamentalists religions are growing in America. He had figures contrasting America with Western Europe.
America was literally founded and populated by religious crazies. Public schools in the US don't teach the whole story behind the Puritan migration to the US. They always frame it as this poor, opressed group fleeing religious persecution in England and wanting to a create a land with true religious freedom. And they end the story there, where it picks up sometime around the revolution.
As rebel8 said, Puritans wanted all kinds of freedom of religion, but only for Puritans. And not even for all Puritans. There were Seperatist Puritans, who wanted a clean break with the Church of England, and the non-seperating Puritans who rejected a lot about the Church of England but still wanted to officially be part of it. And they didn't like each other, at all. Rhode Island was founded because the non-seperating Puritans banished a Seperatist Puritan, who was preaching a little too much religious tolerance, from Massachusetts.
Then you had the Quakers, who the Puritans essentially outlawed in their colonies, and even went so far as to hang them for the crime of being a Quaker in Boston. England actually had to intervene, eventually revoking the Massachusetts colonial chater, and sending in their own governor to lay the law down and force compliance with the Toleration Act, which decriminalized being a non-Anglican Protestant.
Yes, England had to force the Puritans to stop persecuting other religions. It's quite the opposite of the story we were told in school.