Jesus Cruz had made good money smuggling aliens into Florida, but he had been caught and the government offered a deal: Help us, and we'll pay you to catch some other smugglers who have been doing your kind of work for free.

So began the investigation and eventual indictment of the sanctuary underground railroad, a case of law versus conscience that has brought to a ground floor courtroom here what may be the sharpest clash of church and state in America since the protests against the Vietnam war.

From the day in 1982 that goat- and cattle-rancher Jim Corbett, Presbyterian minister John A. Fife and other southwestern Christian leaders announced their plan to help Central American refugees enter the United States illegally, the Sanctuary Movement has made a fetish of open meetings and media interviews -- an unconspiratorial conspiracy by news release.

But U.S. Immigration and Naturalization Service investigators, apparently to ensure that the professed openness was not a ruse, sent paid informers and undercover agents to infiltrate the movement. Cruz is now the key witness in the government's case against Corbett, Fife, Roman Catholic priests Ramon Dagoberto Quinones and Anthony Clark, nun Darlene Nicgorski and six church lay workers. He posed as a volunteer ready to help refugees and brought in two undercover INS agents.

"Our people were so guileless the agents could have brought Adolf Hitler to the meetings and he would have been accepted," said Robert Hirsh, a Tucson attorney representing Fife.

No matter how pure the motive, federal prosecutors have pointed out, conspiracy to smuggle, transport and conceal illegal aliens is against the law. The 11 defendants here face 67 felony counts, each carrying a possible five-year prison sentence; and U.S. District Court Judge Earl H. Carroll is known to believe in stiff sentences.

During jury selection this week, a prospective juror who expressed sympathy for the Sanctuary Movement was asked by Carroll if trial evidence might change her mind.

"Not even remotely," she said. Several defendants laughed, and Carroll admonished them that their reaction "doesn't give any dignity to your cause." At one point, Carroll called this "in a simplistic sense, a smuggling case," and a defense attorney objected.

The government appears determined to discourage a movement that has already spread nationwide to more than 270 churches and synagogues -- and to two cities, Cambridge, Mass., and Berkeley, Calif. -- that have declared themselves sanctuaries. Along with a handful of university groups, they offer refuge to aliens fleeing the civil wars in El Salvador and other Central American countries. Corbett estimates that his group has helped as many as 4,000 refugees in the last four years.

Government pressure reportedly has led to divisions within the sanctuary movement. Some members want more emphasis on ending U.S. support for anti-Marxists in Central America and less emphasis on the Sanctuary Movement and the expensive legal fights.

"Some parts of the movement are interested in charity work for refugees and some are interested in lobbying for a change in U.S. foreign policy," said National Sanctuary Defense Fund chairman Gustav Schultz, here to observe the trial. "That just illustrates the diversity of the movement." His group has so far collected $600,000 in pledges and contributions of the $850,000 it estimates it needs for this trial.

In the wood-paneled courtroom just a few steps from the baked concrete streets and scraggly palms of downtown Tucson, the defendants concentrate on the expected two-month trial ahead and their effort to cut through the bonds of criminal court procedure to give the jury some hint of why they are there.

"I certainly don't want to go to jail," said Corbett, a goateed, 52-year-old Quaker who lives in a concrete-block house here with his wife, Pat, a research technician, and tends his goats, mules and chickens when not in court or busy with the movement. "At the same time, if it comes around to that, it is a price that we have to pay to keep the process going."

Carroll has asked prospective jurors their reactions to the unusual brand of suspect in this case: Three defendants are wearing their clerical collars to court, and Corbett says his criminal record consists of citations for failing to make a complete stop in 1962 and providing an insufficient safety chain on a trailer in 1971.

A federal jury in Texas, allowed to hear evidence about Central American atrocities and the Sanctuary Movement's desire to save lives, in January acquitted movement worker Jack Elder, accused of illegally transporting an alien in his car. A second federal jury later convicted Elder on a second charge and he was sentenced to spend 150 days in a halfway house.

Carroll, at the urging of prosecutors here, has barred testimony about civil war in El Salvador, U.S. foreign policy, international law or the defendants' religious motives. Hirsh said he does not know whether this means that none of the defendants can be asked why they helped the refugees.

"Isn't that the case?" he said.

Since the investigation began, the Immigration and Naturalization Service has handled the Sanctuary Movement and its leaders as gingerly as a ticking bomb. The movement's notion that illegal aliens may avoid arrest in churches such as Fife's Southside Presbyterian under the ancient principle of sanctuary has little basis in modern law, but government agents realized from the start they would risk public outrage if they tried to break into a church and drag away refugees.

One investigator's memo in the court record warned that movement leaders were out to achieve martyrdom. A Border Patrol agent's report said the movement would be glad to show "that the U.S. government thinks nothing of breaking down the doors of their churches to drag Jesus Christ out to be tortured and murdered."

Corbett said that since the movement began, no government agent has entered a church to arrest an illegal alien seeking refuge there. Instead, he said, prosecutors hope to kill the movement by intimidating its leaders. One attorney said all 11 defendents were offered a bargain: They could avoid jail if they would plead guilty to failure to report an illegal alien, a misdemeanor. Three earlier defendants, two not in the movement and one under family pressure, accepted the bargain, but the 11 now on trial turned it down. The government earlier dropped charges against two nuns, apparently because of insufficient evidence and a degenerative disease suffered by one of them.

In what defense attorneys believe was a move to lessen the chance that jurors would hear any comment about the movement's motives, the prosecution has announced that it will not introduce nearly 100 hours of tapes of movement meetings, mostly at Southside Presbyterian, made by Cruz and another informer.

Assistant U.S. Attorney Donald M. Reno Jr. also said he would not call informer Salomon Delgado Graham or INS investigator James Rayburn to testify.

Graham, a convicted alien smuggler, also had been accused of providing prostitutes to field hands. Defense attorneys said he and Rayburn would have been bad witnesses and would have given the defense a chance to probe irregularities in the investigation.