As the December deadline for deployment of new nuclear missiles in Europe grows near, the powerful influence of West German churches has become a political target in the national debate over the morality of nuclear weapons.

For the past five days, more than 140,000 people congregated here for a giant Protestant church festival. Before the antinuclear movement began to flourish in recent years, fewer than 20,000 people were known to attend such semiannual gatherings.

Although the occasion was intended to inspire a renewal of Christian virtues through films, exhibits, musical shows and prayer services, the sessions were dominated--as widely expected--by strong exhortations from well-known politicians. The conference was climaxed by a massive rally Saturday night with 80,000 people protested NATO's plans to station 572 cruise and Pershing II missiles in Europe. Many of them wore violet scarves bearing the motto: "The time has come for an unequivocal no to mass destruction weapons."

The strong German tradition of church influence over political views has intensified the nuclear debate here. Two bishops, Hans Heinrich Harms and Joachim Heubach, refused to participate in the festival because they felt its religious themes were exploited by the peace campaign.

The Protestant assembly's president, Erhard Eppler, a leading Social Democratic opponent of the missiles, denied that the festival was distorted in favor of the aims of peace activists. It was largely his insistence that the antinuclear supporters be allowed to carry out their demonstration on the fringes of religious events, however, that provoked the furor among the Protestant hierarchy.

Harms said that he found it intolerable that peace activists would wear their protest scarves to church services.

He and other clergymen have voiced alarm over the increasingly strident political nature of the religious events. Two years ago, at the last festival in Hamburg, antimissile protesters disrupted the festival by heckling then-chancellor Helmut Schmidt and throwing pig's blood at his defense minister, Hans Apel.

Eppler has drawn strong support, however, from other Protestant clergymen as well as civic and political leaders, who contend that the antinuclear movement raises the most overriding moral issues of our time.

"We should not be worried by a few scarves," said Hanover Mayor Herbert Schmalstieg, "but rather the risks of nuclear war created by missiles in the East and West."

Former West German chancellor Willy Brandt, speaking to a crowd of 15,000 young people at this year's festival, deplored the arms race and warned that "the primacy of political leadership has become a fiction because those at the control of destruction machines in East and West have become objectively stronger."

Such charges by Brandt and other opposition politicians were rebutted by government officials, including Defense Minister Manfred Woerner, who criticized attempts to challenge the national defense "on moral grounds."

Woerner said he realized the good intentions of the peace movement, but said that such attacks "endangered our ability to protect ourselves."

In an article published in a Protestant weekly newspaper as the festival opened, Chancellor Helmut Kohl appealed to the public not to succumb to the lure of pacifist doctrine.

"In dealing with those who do not exclude war as a means of policy, faith in the power of love is not sufficient," Kohl wrote. "They must be restrained from the temptation of evil."

The controversial marriage between church and politics in Germany has dominated social forces ever since Martin Luther revolted against the pope five centuries ago.

Two wars in this century may have uprooted the ties of native towns, but many West Germans still find important affinities between their church and political party. Reform-minded Protestants often vote as Social Democrats, while Catholics in the south and Rhineland generally identify with more conservative Christian Democrats.

In the current nuclear debate, the Roman Catholic Church has shied away from any strong statement on the wisdom of nuclear weapons as a deterrent to war. Indeed, some West German Catholics have criticized the clerical leadership for not going as far in their condemnation of nuclear weapons as American bishops did in their recent pastoral letter.

Protestants, who make up about half of the 55 million Christians in West Germany, have formed grass-roots groups such as "Life Without Armaments" to work closely with antiwar activists in organizing demonstrations against the missile deployment plans.

The religious pacifists frequently cite Christ's Sermon on the Mount with its message that peacemakers are blessed and that a good Christian should not return evil for evil. Such Protestant leaders as Eppler also have advocated partial unilateral disarmament as a way to encourage cessation of the nuclear arms race.

Yet the bitter dispute over the role of peace activists within the church reflected growing fears here that some clergymen may condone acts of civil disobedience, such as sit-ins at missile sites this fall, that could turn violent.