The FBI unconstitutionally moved to charge one of its agents, a Mormon, with espionage to kill an investigation of FBI favoritism toward Mormons and used the agent's religion to coerce damaging statements from him, the agent's attorneys have argued in papers filed here.

Court papers released today in the case of former FBI agent Richard W. Miller, 47, alleged that Los Angeles FBI chief Richard T. Bretzing, a Mormon bishop, repeated to Miller the Mormon "five steps of repentance" for confessing sins before warning him that he was subject to arrest for his dealings with a Russian emigre, Svetlana Ogorodnikova.

Miller's attorneys, calling for dismissal of the charges on constitutional grounds, said the FBI had quietly allowed the resignations of two other agents in New York and Los Angeles who had been suspected of compromising government secrets during sexual liaisons with suspected Soviet agents.

The bureau also failed to charge another Los Angeles agent, John Hunt, with whom Ogorodnikova also claims to have had sexual relations.

Miller was charged with espionage, attorneys Joel Levine and Stanley Greenberg said, because he was "a pawn in a much larger internal FBI struggle to dispel allegations that ranking officials of the FBI office in Los Angeles were systematically showing favoritism toward agents of the Mormon persuasion working in their office."

A former high-ranking Los Angeles agent, B. Matt Perez, has filed a federal complaint saying he was discriminated against because he is Catholic.

In a declaration filed with the papers, Miller said Bretzing's Sept. 29 reminder of the Mormon rules for admitting sins "had a tremendous impact upon me." He said that because of that and his supervisor's assurances that he would not be charged or lose his job, he then confessed to having accepted money from a private investigator for small favors such as license checks when he was an agent in Riverside County.

The Riverside incident is not mentioned in Miller's indictment, but his attorneys indicated it helped change the bureau's attitude toward charging him. The attorneys argued that the charges should be dismissed since some of Miller's statements were unconstitutionally coerced and because he was the victim of selective prosecution because of his religious affiliation.