United Mine Workers President Arnold Miller, who has tried everything else, is now seeking to bring the coal industry to its knees - in prayer.

Miller has given his blessing to a "National Day of Prayer in the Coalfields," a projects organized for this Sunday by a retired Pittsburgh industrialist and free-lance labor peacemaker who is touting the idea of prayer as the ultimate collective bargaining tool.

Beyond that, there are conflicting versions of Miller's plans.

Wayne T. Anderson, the project's organizer, said Miller has agreed to attend two Sunday prayer rallies and to begin "marathon bargaining under the umbrella of prayer" if the six-week-old coal strike isn't settled by the weekend.

Alderson also said Miller told him he would kick off the bargaining marathon by showing a film on the power of prayer in labor-management relations, featuring a project that Alderson ran while he was vice president for operations at Pittron, a Pittsburgh foundry. Alderson claims his idea of bringing people closer together through prayer (which he calls the "Value of the Person: Love, Dignity and Respect") vastly improved labor relations at Pittron but acknowledges that he was fired for his efforts.

A UMW spokesman confirmed that Miller would try to attend at least one of the two prayer rallies Sunday in Waynesburg, Pa., and Powhatan Point, Ohio, but said he didn't know anything about any of the rest - including reports that Miller would seek to bring prayer to the bargaining table this weekend.

The spokesmn issued this carefully worded statement on Miller's behalf: "Coal miners believe in the power of prayer and we appreciate Mr. Alderson's concern and effort. We certainly support all well-intentioned moves to bring about peace and understanding in these troubled times. Officials and members . . . will undoubtedly join in these events in ways that are appropriate and physically possible."

Asked if this meant Miller was endorsing the prayer movement, the spokesman said yes. As for attending the rallies, he said, "It is impossible to know at this point what the negotiating situation and demands will be this Sunday."

Bargaining was proceeding yesterday - reportedly without benefit of prayer - at the offices the Federal Mediation and Conciliation Service, which has resorted to everything short of heavenly intervention to keep the talks on track, with middling success.

Meanwhile, Alderson has encountered mixed results on other fronts.

The Bituminous Coal Operators Association, the industry bargaining group with which the UMW has been negotiating on-and-off since early October, said it, too, believes in prayer but stopped short of endorsing Alderson's venture. "Our members will participate as they think appropriate," said a BCOA spokesman.

Gov. Jay Rockefeller of West Virginia, the state which has been hardest hit by the coal strike, will gratefully pursue any avenue to a settlement. He issued a proclamation endorsing the prayer day last week. "It was a standard proclamation," said an aide, "you know, like V.D. Month or Heart Month."

Alderson said he is expecting similar proclamations from governors of other major coal states, although none had been issued as of yesterday, and maybe even a friendly word from the White House. He claims the backing of "thousands" of individuals, including mayors of coal towns, individual coal operators and rank-and-file miners.

Alderson, 51, a coal miner's son who is now devoting his life full-time to the coalfield prayer movement, said he sees the rallies as a "face-saving way for both parties . . . to come to grips with the real issues of the heart."

The real issue in the coal strike is labor stability and "you can't negotiate true stability . . . it can only come through respect and dignity at the mine site," said Alderson. "It's so simple it's spreading like the flu," he added.