He isn't looking forward to it, but for the Rev. Maurice Dingman, the Catholic bishop of Des Moines, "the time is coming" to think about a stretch in jail. He is aware that in the early church, a prison record for defying the Roman Empire was all but a job requirement for a bishop. Dingman knows also that Martin Luther King's most prophetic call to conscience was his "Letter From a Birmingham Jail."

Many people think Dingman deserves to be locked up. At 71, and after being a bishop for 17 years, he is becoming something of an unholy terror. About the Caesars in the Pentagon and their Central America strategies, he wrote last summer that, "We are drifting inevitably toward war. The signs are obvious for all to see." Earlier Dingman took a conspicuous part in a protest outside a Strategic Air Command base in Nebraska. He didn't hop the fence or block the roads, but he gave blessings to the demonstrators who repainted the SAC entrance sign from "peace is our profession" to "war is our profession."

In dozens of sermons, Dingman has spoken out against governmental violence, corporate abuse of power in the Farm Belt, cowardice among politicians and his own personal feelings about the current lack of leaders. As a citizen, he is uneasy: "I look at the United States, and I become fearful."

Dingman himself is seen as a leader; that's what nags at him. In a conversation the other morning in his Des Moines apartment, which is a first- floor walk-in near a poor section of the city, he spoke candidly of the problems of leadership. "Where do you go, and how far do you get ahead of your people?" he asks. "Where do you place yourself?"

In Iowa and the other farm states, Dingman is known as a fierce opponent of the forces destroying family farms. He refers to the land ethic and quotes the teachings of Pope John XXIII and Pope John Paul II. Then he applies the theories to the forced liquidations, bank closings, high interest rates and low prices, suicides and despair that are the nails being hammered into the farmsteads of the Midwest.

Along with other Catholic bishops who are now drafting a pastoral letter on America's flawed economic system, Dingman sees unaccountable financial power as a major threat. "There is a grave temptation in our system of capitalism that a corporation will use the land to its advantages to gain an undue profit. I'm not saying it's wrong to work for a profit, but I say it's terribly hard to control that profit motive. If they can make a dollar, they're usually going to make it. And if it destroys the land, it doesn't matter. But a farmer doesn't view land as a commodity. Farmers understand that land has a social significance. . . . If corporations in Chicago own land in Iowa, do you think they care what happens to the land as long as they're making a profit and can tell their shareholders that they will get big dividends?"

Dingman, the son of a southeast Iowa farm family and whose nephews still work the land in that area, is revered in the Midwest for his role as part patriarch and part hell-raiser. In a February gathering of thousands of farmers at Ames, Dingman quoted the prophets Amos and Isaiah and delivered a fiery speech worthy of his heroes.

Rousing the crowd is one thing, uniting it another. Dingman has been telling the farmers to get over their useless factionalism: "It is difficult to get the farmers to overcome their individualism and to organize themselves. Every other segment of our society organizes, and then they have clout and can get things done. . . . There is need for government legislation, but there is even greater need for a cooperative collective-bargaining approach on the part of the farmers themselves."

Dingman has no political or economic base, only a moral one. He regularly testifies before the agricultural committees of Congress. He is sought out because few regional leaders are in closer touch with the families that are feeling the pain.

By his years and by his achievements -- he was the host for Pope John Paul II in his 1979 visit to an Iowa farm -- Dingman has earned the right to ease up. Instead, he questions himself -- that his commitment is not strong enough, that he has moved gingerly. He recalls waiting 12 years for "the right circumstances" to sell his bishop's mansion and move into an apartment. On the Catholic hierarchy's 1984 peace letter, he says, "I'm disappointed that we didn't move faster."

What hounds a man like Dingman is that the more he hears he is ahead of his people, the more he realizes how far he lags behind his personal goals. The public leader wars with the private idealist. "I'm struggling with wen to retire," he says, "and devote myself to crucial issues full time." Perhaps he will end up in jail after all. If so, his 70s will be the years of reconciliation: of words of defiance with actions of defiance.