School prayer - including local and state ''moment of silence'' laws - is triggering a roar of controversy that could come to a head later this year. The issue has kept civil liberties groups in combat with religious fundamentalists and others for over two decades, since a landmark US Supreme Court ruling in 1962 effectively barred prayers from the public schools.
But the tide may be changing. A growing number of communities across the United States are clinging to Bible readings, prayer ''moments,'' and other religious exercises, despite court rulings against them. Congressional interests , particularly those in sympathy with the so-called ''religious right,'' are pushing legislation that would open the classroom doors at least a crack for religious exercises. And they have a powerful advocate: the President of the United States.
In proclaiming 1983 as the ''Year of the Bible'' some weeks back, President Reagan said the time is right to ''restore God to the classroom.'' In March he sent Congress a proposed constitutional amendment to restore government-approved prayer to the public schools and other public institutions.
Until recently, some school prayer opponents - including the American Civil Liberties Union and Americans United for Separation of Church and State - seemed ready to write off the administration's thrusts to put religion back into the classroom as political rhetoric designed to appease fundamentalists and others. Last year, neither a similar administration-offered amendment nor a bevy of bills designed to reenroll prayer in the schools had enough political clout to reach the floor of either house of Congress.
Analysts say they still may not have picked up enough steam to muster congressional support. However, the school prayer issue is by no means on the back burner. Why? Among other things:
* A move by the President to reenlist the support of fundamentalists and other religious groups for his likely bid to return to the White House. Some saw his recent open embrace of religious ideals and his attack on ''Godless'' societies as clear evidence of such a move. In deciding what issues to emphasize to solidify this support, the President may see much broader public backing for some form of school prayer law than for aid to private and parochial school education (which he also supports).
* A more conservative and ''noninterventionist'' Supreme Court. This court will likely leave to the states and local communities the resolution of ''moment of silence'' and other classroom-related prayer disputes, unless it discerns clear-cut First Amendment violations. However, the court is not likely to reverse its 1962 decision on school prayer very soon.
* The states' stubbornness in keeping ''moment of silence'' statutes on the books. Despite several court orders restraining them, more than a dozen states have stood their ground on this issue. Many of the laws are being challenged. But the wheels of justice grind slowly.
The moment-of-silence laws are right now at the very center of the school prayer controversy. In defending them, state legislatures and local school boards insist the laws permit voluntary prayer and do not assault the Constitution's wall of separation between church and state. Others, however, see these school-allowed pauses as religious activities, in clear violation of the First Amendment.
State courts and lower federal courts, as well as state lawmakers, are being put to the test. A federal district court in New Mexico recently invalidated a law providing for a one-minute period of silence for ''contemplation, meditation , or prayer.'' By contrast, anAlabama district court judge ruled praying in the classroom entirely valid. He challenged the US Supreme Court's authority in an area which, he said, rightly belonged to the states. Associate Justice Lewis Powell issued an injunction against Alabama's school prayer law while a federal court reviews the lower-court ruling.
A moment-of-silence statute was also struck down in Tennessee late last year. But state legislators have since passed a new law that does not mention the word ''prayer.'' Further legal action is almost certain.
More court action is expected over New Jersey's minute of silence in the public schools. The pause for prayer was passed by the Legislature over the governor's veto. But the state attorney general says he won't enforce the law.
Several related cases are currently in litigation. Among them: a suit brought by the American Civil Liberties Union and parents of a fifth grader in Bristol, Virginia, to halt a 41-year-old practice of Bible teaching in the public schools; and a suit in federal court in Washington State to stop a planned religious assembly at a local high school.
President Reagan's proposed constitutional amendment reads: ''Nothing in this Constitution shall be construed to prohibit individual or group prayer in public schools or other public institutions. No person shall be required by the United States or by any state to participate in prayer.''
Despite the apparent nonmandatory emphasis, opponents say this amendment is intended to go beyond the ''voluntary'' aspect by getting states and school personnel involved in the process. A spokesman for Americans United for Separation of Church and State points out that a White House fact sheet on the amendment says ''states and communities would be free to select prayers of their own choosing'' to promote in schools and other public places.