West German Protestant elders upstaged by antinuclear activists

Amid the peals of church bells, West Germany's vast biennial Protestant church assembly (Kirchentag) opened in Hannover Wednesday, decried in advance by critics as an antinuclear peace festival.

The five-day event, mixing prayer services with debates about the moral legitimacy of nuclear arms, has been all but taken over by Protestants campaigning against the planned deployment of American medium-range nuclear missiles here in six months.

Their violet-colored scarves, bearing the motto ''Return to life. Now is the time for an uncompromising 'no' to mass-destruction weapons,'' have already worked like a red rag to the bulls of the West German political establishment. Before the diverse gathering even began, Interior Minister Friedrich Zimmermann alleged that it would be subverted by Kremlin-influenced militants.

The approach of the deployment deadline for the United States weapons has opened deep rifts within West Germany's estimated 27 million Protestants.

The rise of West Germany's peace movement has transformed the Kirchentag from a sedentary gathering of church elders into a youth-dominated mass event. Some 60,000 people attended the 1981 gathering in Hamburg, and up to 200,000 are expected this time.

Erhard Eppler, who has been elected president of the Protestant lay council, hopes this year's Kirchentag will be marked by a reconciliation between the peace movement within the church and its critics.

The main Protestant groups that have organized antimissile demonstrations in the last two years are represented with stands at the giant ''possibilities market'' - one of the centerpieces of the sprawling assembly. Drawing their moral case from Christ Jesus' Sermon on the Mount, they favor radical, unilateral disarmament.

Other groups accept the principle of defense but want an end to all ''offensive'' weapons - a distinction that other Protestant defense experts say is impossible to make.

A third movement, including such distinguished Protestant laymen as Klaus von Schubert, head of a national armed forces academy, has formulated proposals for a gradual, balanced nuclear disarmament.

But the Kirchentag is not the sort of forum at which such concrete proposals could be adopted. It is more likely leave a diffuse impression of a community in fear of nuclear confrontation which has a growing mistrust of its own government's and alliance's ability to achieve real disarmament.

Missiles are not the only issue at the festival. Chancellor Helmut Kohl, along with his conservative government, will be under attack for his policies on employment, social welfare, ecology, and foreign aid.

These themes give the Protestant church an air of self-questioning effervescence in which Christian fellowship is tempered by a deep anxiety about the future.