Deacon Jimmy Shea of Our Lady of Angels parish was in a restaurant early last week when an elderly man who owns a local insurance company surprised him by asking him to explain "why the bishops are doing this."

"I've worked very hard to get where I am economically, and I give my fair share to the church . . . ," Shea said the old man explained. "What do they know about the economy? I thought they were to tend to souls."

"I told him they're not trying to take your money away," Shea said. "I told him they are teachers . . . ."

What the nation's Roman Catholic bishops are proposing to teach -- when national politics are tilting toward conservatism and Catholics' politics are doing the same -- is the duty of government to redistribute income.

They are studying a draft pastoral letter on economic justice, likely to be issued next year, that advocates driving the unemployment rate down to 3 or 4 percent, raising welfare benefits and preserving the progressivity of the tax structure so that, in relative terms, it takes more from rich than poor.

The letter never mentions President Reagan but seems to conflict with his economic policies. It was issued the weekend after Election Day. To have issued it earlier would have been to politicize it, its drafters said.

The people in this small ethnic city where half the population is Catholic are among those to whom it is addressed.

Most people have not read the draft, but the letter was front-page news and the lead story on TV for most of the week.

In Joan of Arc parish, the Rev. Thomas J. Needham said he is hearing the same things as Shea.

"These are people who love the church, and they're asking why is the church getting into that . . . ," Needham said. "The election has a lot to do with that, with the bishops arguing with the candidates, New York Gov. Mario M. Cuomo and Geraldine A. Ferraro. After services last night one man said to me, 'The church is going to start losing people if it keeps this up. It's none of the bishops' business how capitalism works.'

"I don't mind that reaction," Needham said. "It means people are being reawakened, shaken up and having to think about the problem of poverty in our country . . . . Mother Teresa said we should give to the point of sacrifice, where it hurts to give. That's the living gospel, and it's not an easy challenge."

As City Manager Frank McGrath said, this is where people "listen seriously" to the bishops, a city where Catholic charities regularly exceed their goals.

The draft letter may have jolted those obedient habits.

"The bishops are stepping into the unknown with this one," said Owen Murphy, editor of the local diocese newspaper, The Catholic Free Press. "For years it was pray, pay and obey. The bishops and pope urged Catholics not to read the Bible for years, just follow the church.

"Now the bishops are saying look at the Bible. It says care for the poor. There is nothing new there, but a lot of good Catholics don't realize it's been there. They don't know what a radical Jesus Christ was. Jesus would make a lot of Catholics very uncomfortable."

Murphy reached down from his desk to pull a letter from the trash basket. It is titled, "To the so-called hypocritical Catholic bishop and priests." The letter asked, "What are you crooked, communist Catholic bishops doing now?"

The Worcester Telegram used more polite but similarly biting prose in assessing the draft.

"This draft version is fatally burdened with the Great Society conviction that more government intervention is the answer to poverty," the newspaper wrote in an editorial last Thursday. "It is shot through with the sentimental notion that some people are poor because others are rich and that wealth should be redistributed somehow. The bishops seem blithely innocent of the knowledge that wealth must be created and that the free enterprise system wins, hands down, over any government-controlled plan . . . . The bishop's letter is imbued with a commendable spirit of charity for the less fortunate," the editorial added. "That is to their credit. But a spirit of charity is not enough when it comes to analyzing national and world economies."

The city's politics are another clue to how the bishops' letter may go down.

According to Rep. Joe Early, the Democrat who represents the district in Congress, registered Democrats outnumber Republicans in the city by about 60 percent to 12 percent. But the city went for Reagan.

Early described his district as increasingly conservative on social issues, a city where "people have worked hard for what they've got. They're not getting rich, but they've got a home and are sending the kids to a good school."

The city that two generations ago was filled with new immigrants from Ireland, Italy, Poland and Sweden now is concerned about tax dollars wasted on social programs.

"Catholics are becoming more affluent," said Bernard J. Cooke, professor of religious studies at Holy Cross, the Catholic university on a hill overlooking downtown Worcester. "I saw one study that said Irish Catholics and Italian Catholics are now among the most affluent of Americans who attend church. They have a history of both spouses working, and they are doing well. A large segment of Catholics voted for Ronald Reagan because he asked are you better off than you were four years ago. He didn't ask if the poor were better off."

The growing number of well-to-do Catholics seem sensitive to poverty, but they exhibit a clear difference with the bishops on how to help the poor.

Tom Kennedy, 34, the vice president of Suffolk Yarn Co., said he "supports the general idea" of the bishop's letter on poverty but disagrees that capitalism is to blame or that the government is the best instrument for helping the poor.

"What they're saying is pushing toward more government programs," said Kennedy, who with his wife Dana, lives in Boylestown, a bedroom community outside Worcester. "I'd rather see the bishops pushing toward the individual. They should raise the consciousness of Catholics and all Christians to the problems of the poor. My problem with it is that they want to give more rein to the government.

"I'd be more comfortable if the church would administer the programs," he said. "There would be less waste . . . . If the bishops convince people that instead of watching a football game on Saturday, it's more important to get out and help some old person insulate their home, then I can go along with them."

John Hunt, a Catholic, the chairman of Shawmut-Worcester County Bank and the president of the chamber of commerce in a city where the United Way and Catholic Charities often exceed their fund-raising goals, said he too has more faith in Reagan-style volunteerism than in government programs to help the poor.

"I totally believe in volunteerism," said Hunt, seated on the eighth floor of a glass tower in downtown. "We can deal with real need neighbor-to-neighbor if people take time to care."

Worcester has few blacks, about 1 percent of the 161,000 here, and about 5 percent Hispanics. There is not much mixing of races, nor is there tension.

Hunt said he fears the bishops' letter might lead to the argument that charities should not give to schools or to the arts until all poverty is erased.

Hunt said the bishops were "right" to speak out. But "these are the bishops' teachings, not church laws. The church doesn't lobby me or this government to do anything. There's no arm-twisiting. To me this is just their regular fund-raising appeal in a different way."

To Charlie Thompson, 64, a retired steelworker, and his wife, Mary, who give more than $800 a year to St. Stephen's parish, the bishops' message is not directed at them -- asking them to give more to the church. They said the letter is like the pastoral letter on nuclear war two years ago -- a good thing to take a stand on, but without much effect in the real world.

Thompson also touched on another matter that has bothered some Catholics: that the church was outspoken on a conservative issue -- abortion -- before the election, but saved its liberal issue -- the economy -- until after Election Day.

"Why didn't they say something when it could have done some good?" he asked. "Before the elections all they wanted to talk about is abortion . . . . They got the pope bumping into Reagan in Alaska.

"You can't tell me they ran into each other just so. That was an endorsement, and now when it's all over they start to talk about the poor people. That's what [Walter F.] Mondale was talking about during the election. Nah, but back then they just wanted to talk about abortion."