As is well known, the US Constitution includes an establishment clause, which is really a disestablishment of any officially sanctioned religious group in the US. Or, in Thomas Jefferson's words, there is a "wall of separation" between church and state (at least, officially). This legal situation has given rise to a lot of issues, one of the biggest being the state constantly having to define what is and is not religion in order to make sure such a thing will not be officially promoted by the state. Another result is the conception of a "marketplace" of religions, a situation in which since no particular group receives official state backing, each group must compete for adherents to survive. This twin factors (and I am sure there are many more) have shaped the ongoing reconfigurations of religious life in the US.
Yet, at the very moment, it seems, Parliament is debating whether or not to disestablish the Church of England. What is particularly juicy about this debate in which MPs argue over whether or not this is blasphemous is that the bill happens to be numbered 666. Although there was, no doubt, some design in the numbering of this particular bill by someone with a good sense of irony. Read a small snippet about it here.