Explosive social issues that once preoccupied Congress appear to be slipping off the congressional agenda this year, victims of divisions in the ranks of proponents and threats of liberal filibusters.

Anti-abortion senators have signaled that they will not push their cause further this year, and the volatile school prayer issue seems to have faded in the face of a modest bit of filibustering.

Of the three major so-called social issues, only the effort to restrict school busing has much life left, and its fate for this year may be decided next week.

In the early fall, proponents were insisting on a full-dress debate on all three issues. Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) promised in October to schedule the debate, but this week Sens. Jesse Helms (R-N.C.) and Orrin G. Hatch (R-Utah) asked him to postpone consideration of anti-abortion amendments until next year, primarily because their backers are divided on strategy.

Hatch said he lacks time this year to move out of committee and onto the floor with his constitutional amendment removing federal courts from abortion cases. Many anti-abortion forces regard the amendment, which would let Congress and the states resolve abortion issues, as too soft.

Meanwhile, a slipping legislative schedule in the waning weeks, in combination with budget preoccupation and the threat of filibusters, have affected a largely symbolic skirmish over the issue of prayer in public schools, which has been desultorily debated all week in the Senate. A Helms amendment, tacked onto the pending appropriations bill for the Justice Department, would forbid the use of any money to press suits challenging prayers in school.

The amendment is somewhat academic because the Justice Department is not involved in any such suits, but it was enough to trigger an off-and-on filibuster from Sen. Lowell P. Weicker Jr. (R-Conn.), whose delaying tactics have prevented the bill from passing. The appropriations bill may itself be academic if it is superseded, as expected, by a continuing resolution providing funds for all departments until next Sept. 30.

Helms said yesterday he has ceased pressing for a final vote on the bill. "Why consume the Senate's time, knowing of the continuing resolution coming along?" he asked rhetorically in a conversation with a reporter. "We'll go at it again next year."

Helms said he would not press the prayer issue again in 1981, although other senators may bring it up in the form of a rider to other legislation.

Weicker accused Helms on the floor this week of delaying the Senate's work "time and again" by tacking social legislation onto appropriations bills. "All this time has been wasted on the Justice appropriation," he said.

"I don't hold in reverence this concept of not legislating on appropriation bills," Helms shot back.

Helms and other senators are preparing for another donnybrook over school busing. The issue was the subject of a Weicker filibuster in September, which has had the effect of postponing passage of the 1982 authorization for the Justice Department.

In September, Helms and Sen. J. Bennett Johnston (D-La.) succeeded in attaching an amendment that would bar federal courts from ordering busing programs to correct racial imbalance and would permit the dismantling of any existing court-ordered plan that buses children more than five miles or 15 minutes from their homes.

Helms said Majority Leader Baker has assured him the Justice authorization would be brought to the floor next week with enough time for a full debate, and he predicted a thorough and lengthy confrontation.

"Baker and I agreed . . . that when it comes up, we'll be allowed to debate it," he said. "I want the Senate to go all night long."