President Carter has deservedly been praised for the moderation of his recent statement on U.S.-Soviet relations, but the Russians are interested not in words but deeds. Above all, one deed: repeal of the Jackson Amendment, which began the unfortunate decline of detente between the two super-powers.

To his credit, Carter has lately made several efforts to smooth things over with Moscow, but the Russians can't seem to forget that our Chief Executive began his administration by subordinating detente with Soviet President Leonid Brezhnev to detente with Sen. Henry (Scoop) Jackson (D-Wash.), one of America's foremost cold warriors.

Carter is belatedly discovering what former Secretary of State Henry Kissinger and two former Presidents - Nixon and Ford - learned long ago: that coexistence with the Soviet Union is not compatible wiht coexistence with Sen. Jackson and the hard-line, belligerent anti-communists he often speaks for.

Jackson and his supporters in Congress and the Pentagon were never happy with the Nixon-Kissinger missions to Moscow in 1972, which launched detente and later led to SALT I and the first strategic arms limitation agreement.

In negotiating their arms-reduction treaty, Nixon and Kissinger at times had to make more concessions to their domestic critics than they did to the Russians. Even so, the critics still regard the treaty as a sellout to Moscow. Moreover, they have been no less critical of SALT II, the Ford-Brezhnev follow-up that was tentatively agreed on at Vladivostok in late 1975,

Sen. Jackson was also the chief opponent of the Nixon-Kissinger-Ford policy of relying on "quiet diplomacy" in dealing with the Kremlin on human rights, especially in connection with Russian dissidents and would-be emigrants.

Contending that the Russians respect only force, the senator succeeded several years ago in putting over what is now called the Jackson Amendment, legislation that required the Soviet Union to permit greatly increased emigration, especially to Israel, as the price of trade and credit relations with the United States.

Kissinger predicted that such overt intrusion into Russia's internal affairs would be self-defeating and he was quickly proved right. Moscow cut emigration from over 35,000 a year to less than 12,000. It also denounced the trade agreement, ending what had looked like a promising opening between the two superpowers.

Naturally, the Jacksonites were delighted when Carter, soon after his inauguration, took up where the powerful senator had left off. First, in launching his sudden demarche on human rights, the new President singled out Russia for particular criticism, with the emphasis again on the treatment of dissidents. For added emphasis, he received one prominent Soviet dissident at the White House and then sent a personal letter of sympathy to a second one living in Russia.

In the wake of this, Carter dispatched Secretary of State Cyrus Vance to Moscow, ostensibly to consummate the SALT II agreement begun under Gerald Ford. To the surprise of Russia - and the American public - Vance suddenly sprang an entirely new and much more far-reaching arms-reduction proposal on the Soviets.

Regardless of its merit or demerits, it was a unilateral package. Unlike the earlier negotiations, the way had not been paved for it, so there was consternation not only in Moscow but also in the capitals of our allies, who also have a vital stake in detente and disarmament.

In the circumstances, the Kremlin rejected it out of hand, but in U.S. cold-war circles the proposal could not have been more benignly received if Sen. Jackson himself had conceived it. Some skeptics, only half jestingly, suggested that he had. In any case, it is the first arms-control package to escape the senator's scorn.

Recently, Carter has been trying to tell the Russians that this package is not a final U.S. position but a negotiating one. It was reassuring to note that in his latest speech on detente, there was a hint that the President is beginning to realize what a bone in the throat the Jackson Amendment is to the Russians.

"Increased trade between the U.S. and the Soviet Union," he said, "would help us both . . . I hope that conditions can be created that will make possible steps toward expanded trade." There is only one condition that can do it: repeal of the Jackson Amendment, along with other discriminating restraints on credit and loans.

Carter and his advisers professed to be puzzled over Russia's failure to respond to the President's recent overtures. Yet as long as the White House and Congress stick with the Jackson Amendment, no amount of sweet talk is going to convince Russia that it has not been singled out for selective pressure.

Carter says he is pursuing an even handed policy on human rights, but what of South Korea, where an undemocratic government concentrates on stamping out human rights on the one hand and bribing U.S. government officials on the other? Despite this sordid policy, Carter's latest message to South Korea is that he will defend it to the death.