ALTHOUGH A Senate filibuster in the last Congress stopped a bill that would have limited Supreme Court jurisdiction over school prayer cases, the next Congress will consider a far more dramatic possibility: a prayer amendment to the Constitution itself, proposed by President Reagan last May.

This misnamed school prayer amendment (misnamed because its provisions would apply to every public institution, not merely schools) would repeal a portion of the First Amendment. Promoted as a measure that would simply "permit children to pray in schools," its actual effect would be awesomely different: It would empower government officials to compose officially approved devotional exercises and to require that these exercises be conducted regularly in public institutions.

The amendment's language is deceptively simple. As proposed by the president, it reads in full:

"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."

The text does not immediately alert us to the specter of state and federal officials determining what theology should be imposed on state or nation. This is because the amendment avoids stating who is empowered to determine the content of the religious exercises to be performed in public institutions. Once that question is asked, however, the answer is clear: whatever officials would, in the absence of the First Amendment, otherwise have authority to control the institutions in question.

The official White House "analysis" states that "the determination of the appropriate type of prayer is a decision which should properly be made by state and local authorities." In the first instance, of course, it would be fully within the power of local school boards to enact the religious exercise of the dominant local religion as the exclusive devotional for local classrooms.

But if the prevailing local liturgy is not acceptable to those who dominate state politics, the state legislature or state department of education may mandate a different package of prayer and scripture to be used throughout the state, by every school district, in every classroom.

Nor does government control stop there. Under this amendent, effective control over religious exercises in schools and other public buiildings may ultimately vest in Congress.

By removing the First Amendment's barrier to government control over prayer in public facilities, the amendment would leave Congress free to prescribe the official religious ritual to be conducted in all federally controlled institutions. If the amendment were ratified, moreover, there would be no constitutional restriction preventing Congress from providing federal financial aid only to states and school districts that provide for uniform religious exercises, in keeping with the regulations of the appropriate federal agency.

There is nothing imaginary in this scenario. It has been customary for Congress to attach similar strings to its spending power. State and local communities receiving federal education funds must now comply with a wide range of federal regulations.

There is now one thing -- and one thing only -- that prevents Congress and the federal bureaucracy from conditioning federal funds on compliance with federal "religious exercise" guidelines: the First Amendment. And it is that very portion of the First Amendment that the proposal would strip from the Constitution.

Because it would wholly remove the subject of "group prayer in public institutions" from the Constitution, the amendment would vest in every level of government the power to establish whatever particular religion can command a legislative majority.

This could lead, over time, to a destructive competition among the more than 375 religions in the United States as each seeks to persuade bureaucrats and politicians to select the liturgy of its sect for regular use in public institutions.

That both government control and secterian content are contemplated is clear: The amendment's White House sponsors flatly state their intention that it overrule Engel v. Vitale, the Supreme Court's 1962 school prayer decision, which itself involved a prayer written by a statewide government agency for exclusive use in public schools, where it was to be offered daily for group recital by "willing" school children. Writing for the court, Justice Black soundly observed:

" (I)t is not part of the business of government to compose official prayers for any group of the American people to recite as part of a religious program carried on by government."

For nearly 200 years, religion has flourished in the United States as a private matter alone. We are at religious peace with one another because we have insisted that the affairs of government not be commingled with affairs of the soul. A constitutional amendment that would abandon that common ground is not one we are knowingly like to approve.