THE REAGAN administration wants to push religious observance into the public schools, and the secretary of education, William J. Bennett, delivered an address the other day in vigorous support of the idea. He went on to denounce the Supreme Court for blocking it. The administration will continue to press, he promised, for legislation, court action and even a constitutional amendment "to help correct the current situation of disdain for religious belief."

But the Supreme Court has been upholding a great tradition that is profoundly right, for reasons that Mr. Bennett weighs much too lightly. The intellectual appeal of Mr. Bennett's position would rapidly fade if, to his misfortune and the country's, the court should ever accept it.

Mr. Bennett cites the religious faith of the Founding Fathers, and suggests that bringing prayer into public school classrooms is merely a return to an earlier and healthier practice. That's bad history, and bad history is always a dangerous guide to policy.

It's quite true that the generation of Americans that wrote the Bill of Rights was one, in general, of clear and firm religious faith. But that faith was far from uniform. References to the common Judeo- Christian heritage slide a little too easily past the vast variety of doctrine and usage that the phrase includes. The First Amendment's prohibition of public support for religion was not enacted by people of no religious belief. On the contrary, they held their convictions intensely and wanted a constitutional guarantee that no other denomination or authority -- even if supported by a majority of the voters -- could impose its religious practices on them and their children. Diversity of belief, not indifference, is the historical foundation of the First Amendment.

Mr. Bennett seems to assume that it would be simple, if only the Supreme Court got out of the way, to fashion satisfactory religious usage for the public schools. There are a lot of school boards around the country that know better. In the rich accumulation of constitutional law that has defined the separation of church and state, very few cases were brought by atheists. Most of the plaintiffs were members of denominations that were minorities in their communities, and went to court to protest the use of political power by the majority to override and coerce the dissenters.

There was a time, speaking of history, when conservatism meant a special concern for the right of a minority to be different, and for the preservation of certain areas into which majority rule was not permitted to reach. Those principles seem to be suffering a bit of erosion in the Age of Reagan. That's a pity, but it's not a reason for people -- least of all Supreme Court justices -- to change their minds about religion in the public schools.