"The First Amendment expresses our Nation’s fundamental commitment to religious liberty by means of two provisions–one protecting the free exercise of religion, the other barring establishment of religion. They were written by the descendants of people who had come to this land precisely so that they could practice their religion freely. Together with the other First Amendment guarantees–of free speech, a free press, and the rights to assemble and petition–the Religion Clauses were designed to safeguard the freedom of conscience and belief that those immigrants had sought. They embody an idea that was once considered radical: Free people are entitled to free and diverse thoughts, which government ought neither to constrain nor to direct. Reasonable minds can disagree about how to apply the Religion Clauses in a given case. But the goal of the Clauses is clear: to carry out the Founders’ plan of preserving religious liberty to the fullest extent possible in a pluralistic society. By enforcing the Clauses, we have kept religion a matter for the individual conscience, not for the prosecutor or bureaucrat. At a time when we see around the world the violent consequences of the assumption of religious authority by government, Americans may count themselves fortunate: Our regard for constitutional boundaries has protected us from similar travails, while allowing private religious exercise to flourish. [...] Those who would renegotiate the boundaries between church and state must therefore answer a difficult question: Why would we trade a system that has served us so well for one that has served others so poorly?"