The Republican Senate rolled over its moderate leadership yesterday and in a victory for conservative Sen. Jesse Helms (R-N.C.), approved the strongest anti-abortion provisions Congress ever has passed.

Already approved by the House, the language would forbid federal funding for any abortion except where the woman's life is in danger.

The Senate acted after also giving final congressional approval to a $695.5 billion budget target for fiscal 1982 that hews almost exactly to President Reagan's program of tax and spending cuts, marking completion of the first phase of the battle of the budget.

The 76-to-20 vote to approve the budget was expected. The abortion vote was not. Republican leaders had hoped to set a precedent for stripping money bills of extraneous, controversial riders and confining the explosive abortion issue to the more orderly process of authorizing committees.

But instead, only minutes after Helms warned wavering members that their votes would be "attentively watched" as an indication of their faithfulness to the anti-abortion cause, the Senate voted, 52 to 43, for a House-approved rider to an appropriations bill that would permit Medicaid abortions only to same a woman's life.

Current law permits Medicaid abortions for poor women also in cases of incest and rape so long as the rape is reported within three days.

The rider -- alternatively attacked as an example of "Cotton Mather morality" and defended as a virtual commandment from Mt. Sinai -- was attached to a $12.8 supplementary appropriations bill to operate the government through the end of the 1981 fiscal year on Sept. 30.

The Senate then went on to approve the huge money bill, 95 to 0, sending it on to conference with the House.

But because the House has already approved identical anti-abortion language, the strict new restrictions are certain to become law for the next four months, as well as probable precedent for the future.

Although Senate Appropriations Committee Chairman Mark O. Hatfield (R-Ore.) tried to portray the vote as a procedural one aimed at purifying the Senate's normally messy appropriations process, the vote was clearly a demonstraiton of the potency of the anti-abortion lobby.

It was mitigated by only one thing: rejection by voice vote, as part of a package of amendments, of a House proposal also to deny abortion funds for federal workers under any newly negotiated health insurance plan financed by the government.

While the pattern of the vote crisscrossed ideological as well as party lines, it also amounted to vindication of Helms' claim that controversial social issues can't be shelved in total deference to economic and other programs designated as higher priorities by Republican leaders.

The abortion fight was almost an all-Republican show as Democrats, welcoming the opportunity to see thenormally more unified GOP tear itself apart for a change, scarcely even participated in the debate.

The debate -- probably the liveliest so far in the 97th Congress -- got off to a slow start until Sen. Bob Packwood (R-Ore.) took the floor to decry what he called a "growing feeling of intolerance in this country, almost of religious moralism . . . a Cotton Mather mentality that is imposing on the country a Cotton Mather morality."

Asserting that poor women who get pregnant as a result of rape or incest will now be denied abortions that richer women can afford on their own, Packwood said it would simply be "tough luck" for the poor.

"I had thought we stopped burning witches in the country . . . but apparently not," he added bitterly.

Rising indignantly in response, Helms denied that the vote was simply one of institutional reform and asserted that it involved whether taxpayers should have to pay for the "deliberate taking of an innocent human life." There was, he said, a "set of instructions that came down from Mount Sinai" about that.

Impatient at the religious analogies, Sen. Lowell P. Weicker Jr. (R-Conn.) protested that the issue was one of law, not religion. "We are not running this country by divine commandment or instructions from Mount Sinai," he shouted. Moreover, Weicker, noting Congress' gradual expansion of abortion curbs over recent years, contended "it won't be long" before government-financed abortions are also denied to save the life of a pregnant woman.

In the midst of the crossfire, Hatfield an abortion foe who said he has consistently supported tighter restrictions, tried in vain to argue for institutional reform. "We cannot tolerate the kind of excess baggage and encumbrances that have been placed on the appropriations process in recent years," he contended, prompting a gesture of help from the one Democrat who joined in the debate Sen John C. Stennis (D-Miss.).

"I'm a committee man," said Stennis, in backing the Appropriations Committee's decision to strike the abortion rider from the House-passed bill. c

Hatfield also even threw in the towel early on the substance of the proposal, noting that the probable Senate conferees on the issue supported the House position.

Both Virginia senators and Sen. Paul S. Sarbanes (D-Md.) voted against tightening the abortion restrictions. Sen. Charles McC. Mathias Jr. (R-Md.) did not vote.

In other action on the money bill, the Senate approved, despite Helms' opposition, $538 million in additional spending authority for food stamps, meaning the program will not face the risk of having to seek another separate appropriation to keep food stamp payments flowing until the end of the fiscal year.

The omnibus money bill increases spending authority by $21.5 billion while rescinding $15.3 billion in previous spending authority -- a somewhat revised version of what Reagan proposed and the House approved earlier this month. In terms of outlays, the bill increases spending by a net of $12.8 billion, pushing spending to within $200 million of the newly revised budget ceiling of $661.4 billion for the current year. The deficit is $58 billion, although it may go higher.