DALLAS -- Faith in God comes easy to Linda Hajek, a social worker among black and Hispanic families at Holy Cross Catholic Church. It is faith in the system that drives her to doubt.

Agents in the Dallas field office of the Federal Bureau of Investigation put Hajek under surveillance from March 1983 to June 1985 because she worked for the Committee in Solidarity With the People of El Salvador (CISPES). Hajek was the coordinator of the Dallas chapter. The FBI, through a Salvadoran informer who infiltrated the group, suspected Hajek was a terrorist keeping guns in the CISPES office next to Holy Cross.

Last week, William Sessions, the new FBI director, announced that six Bureau investigators were being disciplined for their harassment of the group. The FBI campaign of "counterterrorism" eventually led to snooping on 169 people and nine other groups. Nothing turned up.

Hajek, a Fort Worth native in her midforties who was a Sister of St. Mary of Namur for 21 years before leaving the order in 1983, smiles wanly as she recalls the FBI episode. She is sitting in the Holy Cross parish hall. Photographs of two 20th-century martyrs -- Martin Luther King Jr. and Archbishop Oscar Romero -- are on the walls. The latest newsletter from the Dallas Peace Center is on the table. In recent years, Salvadoran families were given sanctuary here.

Sure, Hajek says, she feels vindicated by the announcement by the FBI, "but let's not be naive. This investigation may be being continued under other names. Most of us involved in Central American work are not just involved in CISPES, which is connected with El Salvador. We're all involved against aid to the contras in Nicaragua, in wanting to see changes in Guatemala and wanting to see the U.S. military out of Honduras. The FBI can use a lot of other informants and keep on investigating. I hope that's not happening."

If such wariness suggests that Hajek is overly suspicious of the FBI and its record of obsession to stifle dissent, the seamier side of the CISPES campaign needs to be recalled. "The Salvadoran plant that the FBI was using against us," Hajek recalls, "later told us that he was instructed to break our chapter any way he could. When weapons couldn't be found, nor anything else illegal, he said his supervisor suggested trying to get involved with me sexually. This guy was a Catholic and I was still in my order at the time, so he balked." The informant, apparently, found the FBI scheme of seducing nuns too disgusting a way to discredit CISPES.

At Holy Cross, most of Hajek's work is with poor families in need of food, job counseling or common survival in the south Dallas neighborhood of Oak Cliff. While a Sister of St. Mary of Namur, Hajek had spent seven years teaching in Zaire. Her work with CISPES was central to her calling, no matter where it took her: standing up for social justice and siding with the powerless.

Keeping faith with that ideal meant that Hajek didn't have time to waste on who might be wanting to harm her. Like most Americans, she trusted the FBI: "I didn't suspect they were investigating us until a reporter from The Dallas Morning News came and said, 'I'd like to confirm some facts with you.' She went through this story. We had never, ever, suspected the FBI would use a Salvadoran as a plant. We knew the man she was talking about, but it had never crossed my mind that he was an informant."

Hajek didn't have much reason to know, as she now does, that the FBI was not particularly bright, even on basic facts: "From some of the Freedom of Information material I saw, it was clear to me that the FBI never understood the differences between CISPES, the Interreligious Task Force on Central America and Sanctuary. All were very different organizations. The FBI just lumped them all together ... Its people were so sloppy."

Neither that botching nor the low-grade snooping on Catholic nuns has sufficiently bothered William Sessions: None of the six Bureau officials has been fired, which ought to be the minimum punishment. Nor have their names been made public. The Dallas agent who worked closest with the informant resigned in 1984, so he's also safe.

Without holding her breath, Linda Hajek is now waiting to see whether Sessions is big enough to write her and the other CISPES workers a letter of apology. If it does come, Hajek plans to send back a copy and ask that the letter be the only document in her FBI file. It may take a lawsuit to remove whatever else is now in it.