Courtly even when flapping most furiously, he swoops down on the transgressors -- from feminists and labor barons to errant diplomats and generals -- like an avenging angel of old-time religion.

And, to the extent that President Reagan departs from scripture, he too can expect thunderbolts from Sen. Jesse A. Helms (R-N.C.), the archangel of true believers. Some of the president's men have been singed already.

In the first days of the Reagan administration, the owlish-appearing Helms, 59, looking more like a schoolmaster or small-town banker than political enforcer, has emerged as the point man for the right wing's efforts to keep the new government from straying off into what they view as the netherworld of the political center.

His stage is the Senate, where, as a prominent member of the president's party, he let not more than four hours of the Reagan administration go by before attacking some initial appointments in order to make his case against any ideological backsliding by the new team.

But his arena is the whole country.

Out there he is the champion, the cheerleader, the guru of an amorphous but apparently large coalition of right-wing conservatives, religious fundamentalists and others who regard themselves as the foot soldiers of a political, even spiritual, revolution that took place at the polls Nov. 4.

It is not clear yet, and probably won't be for some time, whether Helms can use the leverage of this attentive, demanding constituency to keep the administration from lapsing into the normal Washington pattern of compromise, consensus-building and expediency. But it is clear that he intends to try, and the prospect is causing some anxiety among pragmatists in the Reagan camp.

During his first eight years as an ideological outsider in Washington, Helms picked up a mastery of Senate rules and procedures that is highly useful to a guerrilla fighter in Congress.

And now, thanks to the Republican takeover of the Senate after the November election, he has also inherited a measure in institutional power. He heads the Senate Agriculture Committee, which will preside over the 1981 farm bill and surgery on the food stamp program, and was elected this year as chairman of the informal steering committee of 25 to 30 conservative Republican senators, constituting roughly half the GOP majority in the Senate.

But it is not so much because of his Senate record or even his new leadership roles that Helms commands attention, and in some cases even fear.

Inside the Senate, he is viewed as everything from a dedicated, principled crusader to a loose cannon. "Maybe some of both," said a more moderate Republican colleague, professing affection rather than malice.

Aside from winning ever-tightening restrictions on government-financed abortions, his portfolio of lasting legislative achievements is thin. And, while some of his other causes such as oppositon to school busing for racial purposes and support for prayers in schools, are gaining legislative support, even some of his conservative allies want to put aside divisive battles on these issues in favor of quick, concerted action on Reagan's economic program. t

Other senators such as Edward M. Kennedy (D-Mass.) and Barry M. Goldwater (R-Ariz.) and George McGovern (D-S.D.), before he was defeated last year, have had constituencies stretching beyond Washington and their home states, but they were presidential candidates.

Among those suspicious of power, especially federal power, Helms has somehow conveyed the image of a man without personal ambition, forced reluctantly into politics and still not sure he belongs there.

He talks unabashedly of God, patriotism, free enterprise, moral absolutes, old-fashioned virtures of all kinds. He can play hardball politics with the best of them, but with an aw-shucks innocence that somehow makes it seem nicer. He appeals simply and directly to people frustrated by the complexities of the world: a man of black and white set on a field of grays.

"The Moral Majority is criticized by others," said Helms in assessing what he calls "the cause" to which he ascribes, "but you get out there in the grass-roots and see who is supporting a spiritual revival and you see the heart of America. And I think it is good. Basically, we're talking about faith in God versus secular humanism."

People who share his views see Helms as "their anchor," said Paul Weyrich, executive director of the New Right's Committee for the Survival of a Free Congress. "On issues of major concern, he's willing to stand alone," said Howard E. Phillips, national director of the Conservative Caucus.

But Helms does not exactly stand alone. He has a formidable array of organizational support out there, including the network of highly sophisticated money-raising, research and propaganda organs of the New Right.

He even has his own modern-day equivalent of a political machine, relying on direct-mail money solicitation to grease the same wheels of elective politics that once ran on patronage and other personal favors.

The North Carolina-based Congressional Club was created to pay off Helms' 1972 campaign debt, but has since gone national, raising $7 million to $8 million last year for Reagan and for out-of-state Senate and House candidates as well as for the election of Sen. John P. East (R-N.C.) and for other Helms home-state favorites.

Reagan alone benefited by $4 million in contributions from what Helms calls "probably the most sophisticated operation [of its kind] in the country." Some of Helms' newly elected Senate colleagues received up to $30,000 each. Helms plays no day-to-day role in the club's operations, but serves as its honorary chairman and "spiritual leader," according to Tom Ellis, a close political ally who directs its activities.

It raised $7 million for Helms' reelection campaign in 1978, and can be expected to be running at full tilt again in 1984, when helms is expected to face a tough challenge by North Carolina's popular Democratic governor, James B. Hunt.

In his warning shot across the bow of the Reagan administration, Helms took aim only at the men around Reagan, but he aimed high.

Reagan had barely gotten off the Capitol grounds on Inauguration Day before Helms took the Senate floor to oppose confirmation of Caspar w. Weinberger as secretary of defense on the grounds that Weinberger, better known for his budget-cutting skills than his defense expertise, had not signaled that he would be tough enough on the Soviets.

Helms also took the unusual step of putting a hold on the nomination of Frank A. Carlucci, whose credentials as a hardliner were also suspect in Helms' mind, as Weinberger's deputy.

And, as chairman of the steering committee, he fired off a letter to Secretary of State Alexander M. Haig Jr. questioning Haig's choice of several high-ranking assistants. Helms later let the Carlucci nomination come up for a vote, but voted against confirmation. As the the State Department, it probably hasn't heard the last from Helms.

"Just sending 'em a message," said Helms the other day, emphasizing that his near-decade of support for the idea of a Reagan presidency remains as strong as ever, even though he makes it clear he needs frequent reassurance.

"My conversations with the president indicate he has no intention of compromising his principles," Helms said, lacing his confidence with a dash of reserved judgment. "I've believed him all these years, and I see no reason to start disbelieving him now . . . so we'll wait and see."

Helms' behavior has raised hackles in the White House as well as the State Department, and officials close to Reagan concede they are restive about the trouble that Helms could cause -- the threat of which could mean powerful leverage for Helms and lead to some "feeding of the alligators," in the words of one apprehensive Republican liberal.

Since firing his opening salvo, Helms claims increased satisfaction with administration appointments and with its consultative efforts. He says he's been assured that prospective appointees are being screened for ideological moorings as well as professional expertise.

But it is a mixed record so far, with the administration giving the New Right more in the way of symbolic gestures than in the way of symbolic gestures than substantive concessions, including putting out a White House welcome mat for antiabortionists in the first hours of his administration.

In the case of Helms' well-publicized lobbying for Fred C. Ikle as undersecretary of defense for policy, officials say Ikle was in line for a major post anyway. Four State Department designees who drew a complaint from Helms are at work pending formal nomination. And John Carbaugh, Helms' hard-charging foreign policy aide, hasn't gotten far in trying to land a job at State.

Within the Senate, Helms drew only East as a supporter in opposing Weinberger, and East plus four others in voting against Carlucci, although many more Senate conservatives have privately expressed unease over some appointments.

"Helms has actually been the calm one so far," said Weyrich, who shares their dismay at some appointments. The difference is that they have avoided open confrontation, at least so far, which has the effect of isolating Helms in the public's eye.

"He does things that a lot of senators don't have the guts to do," said Phillips. But some senators, while giving Helms high marks for sincerity in his conservative convictions, suggest he also enjoys the limelight and needs to carve out a role separate from Reagan to keep his cause in motion.

For all his uncompromising talk, there is also a streak of the practical politician in Helms. Take the matter of farm subsidies. Helms yields to few in his opposition to government handouts and dedication to a free-market economy, and yet he represents a farm state and so supports farm subsidies.

"The question is how many more farms are we going to allow to go down the tubes because of economic conditions not created by them (farmers) and over which they have no control," said Helms, using a rationale that others use for their pet projects, including projects that Helms wants cut. Farmers, he adds, will sacrifice when others sacrifice too.

Helms was born and reared in Monroe, N.C., the son of a policeman who went on to become Monroe's combination police and fire chief. After college and service in the Navy, he dabbled in conservative politics (he was a Democrat until 1970, shortly before he ran for the Senate), worked as an aide to two conservative Democratic senators and became a popular television commentator.

How did he get the way he is? He cites the influence of his father, an English teacher who taught him conservative economics and a school principal who taught his charges that they could achieve anything, even the presidency, if they worked hard enough.

Well, what about the presidency? he was asked.

"Oh, pshaw," responded Helms, "I'd sooner run for the county line."