THERE IS SOMETHING truly grotesque in the protestations of high administration officials-- aired in Milton Benjamin's story in The Post yesterday--that this government is keeping the faith so far as efforts to slow the spread of nuclear weapons are concerned. The truth is very nearly the opposite. And yet we have, for instance, the deputy secretary of energy, W. Kenneth Davis, saying this: "People have gotten the idea that this administration is somehow less interested in retarding proliferation than previous administrations. That simply is not true. I think we are as much concerned--perhaps even more concerned--about slowing down or retarding it."

If Mr. Davis and his colleagues wish to know where people (we are among them) have gotten this strange "idea," they need look only as far as their own public statements and actions since the Reagan administration was installed. From just about day one, the president's appointees have been making plain their contempt for the old (Carter, Ford and congressional) policy of seeking to impede the flow of potential weapons-making materials and technology to countries that have given reason to suppose they might actually use these things for the production of explosives or which have refused to accept adequate safeguards for their proper, peaceful use. We have been told that this former policy was an unworkable and stupid effort.

And we were told it again in Mr. Benjamin's story by the director of the Arms Control and Disarmament Agency, Eugene Rostow. "The old methods to which earlier administrations and many people in Congress are still committed rest on illusions," he said, "--the illusion of American omnipotence and the illusion that the United States Congress has jurisdiction over the policies of many other parts of the world. We want to get rid of the nostalgia for an epoch of monopoly that is gone. There is absolutely no use trying through export controls to achieve what can't be achieved."

Apart from the piquancy this statement may be expected to have for Europeans currently wrestling the administration for the right to go ahead with their exports for the Soviet gas pipeline, it is of interest mainly because it takes you nowhere. And in that sense it is as good a guide as you will get to any so- called nuclear nonproliferation policy in the Reagan administration. Of course there were weaknesses and uncertainties and risks in the old policy. How could there not be in a matter so complicated--politically, economically and technically--as this? But that didn't make it any less urgent to try to inhibit the spread of nuclear explosives to ever more countries abroad. Besides loosening up restrictions on the transfer of weapons-potential material and technology overseas and claiming that all this will, somehow, give us a mysterious new clout in preventing the spread of weapons, can anyone tell us what the Reagan policy is?