A union of government and religion tends to destroy government and to degrade religion."

--The 1963 Supreme Court decision outlawing prayer in public schools

FEW THEMES are so central to our nation as the separation of church and state. When the Supreme Court effectively banned organized school prayer in a pair of decisions in 1962 and 1963, that enlightened doctrine seemed to have been carried to its logical extreme. No longer could religious groups seek state approval for public school prayers and Bible readings. For even prayers designated as "voluntary" had proven compulsory in practice, in one famous instance, only one student turned down a school system's "voluntary" prayer option over several years' time.

Last week, the nation took a dangerous step backwards, toward the day when worship in public schools was considered acceptable. Under pressure from fundamentalist religious leaders, President Reagan formally endorsed constitutional amendment to allow voluntary school prayer. The President's Bible Belt supporters were plainly ecstatic. Moral Majority leader Jerry Falwell exulted. "After 20 years of the expulsion of Almighty God from the public schools of our nation. I think this is the light of the tunnel we have all hoped and worked and prayed for."

We are not so pleased, for several reasons. Permitting prayer in public schools may satisfy the President's religious supporters, who are also at the forefront of efforts to circumvent Court decisions legalizing abortion and recommending busing as a solution to desegregation. But that is all.

It will not please those who--like the National Council of Churches and the American Jewish Congress--rightly believe that, religion does not need, and should not have, the sponsorship or support of the government." Voluntary and nonsectarian in name only, codes allowing group prayer inevitably supported entrenched religions at the expense of less widespread ones. And because of the peer pressure that's probably unavoidable in school settings, students who had no desire to pray often found themselves compelled to join in--effectively denying their right not to exercise their religious preferences.

The President's proposal also troubles us for another reason. The Constitution should be as insulated as possible from fleeting political caprices; instead, it should reflect the more timeless values of the nation, not controversial policies like organized school prayer. Yet the President has chosen to ignore this custom, seeing the wide support it enjoys among his partisans.

Government obviously should not act antagonistically towards religious groups, but instead should provide a neutral setting in which religions can flourish without excessive entanglements with the State. But as one Supreme Court Justice wrote of a group prayer statute two decades ago. "The breach of neutrality that is today a trickling stream may all too soon become a raging torrent." In view of the President's proposal last week, we can only hope that his diagnosis will not soon prove accurate again.