The nuclear freeze issue is knocking on the President's door once again - this time in the form of an exchange between his national security adviser (who happens to be devoutly Roman Catholic) and the National Conference of Catholic Bishops. The latter have endorsed a proposed pastoral letter opposing the use of nuclear weapons.
One question Washington now faces is whether the nuclear weapons freeze movement (1) has peaked and will have to be paid only lip-service as arms talks proceed, or (2) is still building and will strongly affect the pace and substance of the negotiations. All indications point to the latter.
The first shoe to drop outside the Oval Office was the nonbinding freeze vote in 8 out of 9 states earlier this month. The second is the pressure generated by a majority of the Catholic bishops - a striking change from the pastoral and political influence much of that same group brought to bear in favor of a military solution in Vietnam two decades ago. A third shoe is likely to be a new vote on a (nonbinding) congressional resolution favoring the freeze concept when the new congress meets next year.
So the political pressure is gradually increasing, not peaking and subsiding. As national discourse grows, Americans will want to give careful thought to the subject. The motive ought not to be fear but a desire to find a way out of a seemingly unbreakable impasse - with all the savings of budget, changes in cold war attitudes, and shifts of resources that would accompany new success in restraining the nuclear arms race.
Fundamental questions call for analysis. Is it really possible to fight a limited nuclear war? If all-out holocaust is deemed inevitable, is it ''immoral'' to use or threaten the use of nuclear weapons? Should the Western alliance adopt a no-first-use nuclear strategy? Is the doctrine of deterrence obsolete? Should the West work for a mutual freeze on nuclear arms to stop further buildup while arms reduction efforts are pursued?
Significantly, these are questions troubling not only the Roman Catholic Church and other religious groups. They have become the burning concern of millions of people throughout Western Europe and the United States. The Reagan administration may charge that the nuclear freeze movement is being manipulated by the Soviet KGB. But, however Moscow seeks to exploit the movement - and it surely does - it would be self-deceiving not to recognize the genuine grass-roots impetus behind it.
It is, moreover, not only ordinary citizens unsophisticated in their knowledge of nuclear matters who are calling for reappraisal of policies. Note, for instance, how many former British defense chiefs, who long participated in NATO planning, are challenging present doctrines. Or that such former US establishment policymakers as Robert McNamara, McGeorge Bundy, George Kennan, and Gerard Smith warn that any use of nuclear weapons in Europe - by NATO or the Warsaw Pact - would inescapably risk escalating into a ''general nuclear war which would bring ruin to all and victory to none.'' They advocate a policy of no-first-use.
The debate seems to be taking place precisely because the US government has not articulated these issues. Indeed, it is in part the loose rhetoric of some in the administration - concerning the ''winnability'' of a nuclear war and the ''survivability'' of populations - that has triggered such strong public reaction. Statements like the one by a high Defense Department official that in a nuclear war people will survive if they only ''dig a hole, cover it with a couple of doors and then throw three feet of dirt on top'' points to a flippant and insensitive attitude.
If the administration wants to defuse the nuclear peace movement, it will have to face up to these issues in a more analytical way. It will also have to demonstrate progress on arms control. Otherwise other mainline churches may also come out against NATO's first-use policy, raising a profound challenge to political leaders. For how can the nation have a reliable defense policy if it is opposed by many religious leaders?
In its rebuttal to the proposed pastoral letter, the White House maintains that its nuclear arms policies are guided by moral considerations, namely the prevention of war and preservation of values. That argument certainly will appeal to Americans, the vast majority of whom would never countenance a weakening of the nation's armed strength. But claims that America's weapons systems are not designed to be ''first-strike'' systems and that its deterrence posture is ''defensive'' may seem undercut by administration plans to go ahead with the new MX missile.
Somehow Mr. Reagan has yet to persuade his critics that he is in earnest about arms control - especially in light of the weakening of the US Arms Control and Disarmament Agency, the apparent doldrums in the START talks, and the fact that the US has bowed out of negotiations for a comprehensive test-ban treaty and the antisatellite-warfare treaty talks. Slightly more hope is expressed for the East-West talks on intermediate-range nuclear forces inasmuch as there could be political repercussions if NATO proceeds with deployment of the Pershing II and cruise missiles.
President Reagan will best address the concerns of the public, including religious leaders, by making headway on arms control. The change of leadership in the Kremlin provides opportunity for a renewed effort, and Mr. Reagan needs to seize it. On one moral point everyone can agree: a nuclear conflict is to be avoided at all costs. No amount of energy, determination, and political will should be spared toward that end.