If you are at all confounded by the conflict over this country's human rights policy abroad, fasten your seat belts.The Senate is about to take up the confirmation of Dr. Ernest W. Lefever as assistant secretary of state for human rights and humanitarian affairs.

And the proceedings promise to be the most turbulent, if not the nastiest, in the Reagan administration's short life. There's a certain irony there. The Lefever nomination has been widely perceived as a sop to the Senate's ultraconservatives, a way of damping down their tantrums over the choice of seeming moderates to top foreign policy making jobs. But the price tranquillity on the right, it's plain, is going to be a tempest from the left.

Lefever has been advised that two full days have set aside for his hearings by the Senate Foreign Relations Committee -- one for the pros, one for the cons -- almost unprecedented for an assistant secretary.

But the format has a certain logic. For what emerges from the public record and a long interview are, in fact, two ernest Lefevers. One is the self-styled, lifetime "true believer" in human rights, the genuine liberal in all aspects of the issue, who was out in the streets participating in sit-ins with civil rights activist Bayard Rustin before, by his account, "Martin Luther King had joined the cause."

This is the Lefever whose biography begins with a PhD in Christian Ethnics from Yale. It includes: welfare worker in his college days; member of the London International Institute for Strategic Studies; Brookings Institutions staff member; teacher of political science at assorted universities; author of a dozen books; constant lecturer; world traveler; distinquished and respected authority on geopolitics.

The other Ernest Lefever is the head of his own highly controversial Ethics and Public Policy Center, once affiliated with Georgetown University, subsequently split off under circumstances some consider cloudy. The center itself draws heavy fire, not just for its policy orientation but for its sources of financial support -- South Africa, for one.

This other Lefever has managed to attract heavy fire from the World Council on Churches and enough violent opposition from other quarters -- the ACLU, the Helsinki Watch, the Lawyers Committee for International Human Rights -- to generate the creation of an "Ad-Hoc Committee of the Human Rights Community" for the express purpose of fighting his nomination.

The committee's initial press release charges that Lefever "represents the antithesis of the congressionally mandated concern for human rights . . . [His] views in fact imply a perversion of internationally recognized human rights values into blind support of "authoritarian' allies coupled with politically motivated denunciations of 'totalitarian' enemies."

Not everything you hear about Lefever, in other words, can be true. At 61, lean and graying he is dogmatic, contenious, impassioned, persuasive, ascetic -- clearly a fellow capable of inspiring the like-minded, while generating violent opposition from those who disagree.

His nomination, in short, confronts the Senate Foreign Relations Committee with a formidable task. It is going to have to sort out scandal-mongering from valid allegations, and ad hominem assaults from honest philosophical and tactical arguments.

Lefever presents a respectable argument. It begins with a pledge to "broaden and deepen" America's human rights concern. He adds a promise to carry out existing laws (antedating Jimmy Carter's human rights crusade) that call for regular public report cards on human rights performance by particular countries around the world and the denial of American foreign aid as a lever against violators.

But he does not exclude an effort to amend these laws in keeping with a four-page, double-spaced draft, for presentation to Secretary Haig and President Reagan, of what he thinks our human rights policy ought to be: the United States as a "shining city on a hill," leading by example; quiet forbearance in the case of human rights repression by "authoritarian" allies threatened by "totalitarian forces; quiet diplomacy instead of "public scoldings"; rare public denunciation, selectively, in cases of gross abuse.

Boiled down, this represents a profound tactical switch from a Carter policy that presumed in principle to make human rights a universal, overriding test. But it is indistinguishable, Lefever insists, from the approach advocated by the new U.S. ambassador to the United Nations, Jeane Kirkpatrick. Her nomination swept through the Senate committee without a dissenting vote.

So why the fuss over Lefever? That's what the Senate Foreign Relations Committee will have to decide if it is to reach a fair judgement not just on Lefever's credentials and qualifications, but on the far more important question of what, in his hands, the Haig/Reagan human rights policy is likely to be.