"Sun-Times vs. Catholics" read the headline on the editorial in the official newspaper of the archdiocese of Chicago. What followed was a no-holds-barred attack in which the Sun-Times was accused of practicing "anti-Catholicism" and "character assassination" worthy of the "Ku Klux Klan," and threatening the right of Catholics to practice their faith.

The cause of all this anger was an article that has never been published in the Chicago Sun-Times and, indeed, may never be published and may not even be a story, according to Sun-Times editor Ralph Otwell.

That the paper was even investigating the financial affairs of the archdiocese prompted the outburst from the official archdiocesan newspaper a month and a half ago. The outburst may yet generate a new defensive tactic for those under investigation by newspapers -- expose the exposers.

The success of this approach is still undetermined, since the Sun-Times has not decided whether to publish what it has found. But it may be a signal that established religious organizations, after several years of newspaper scrutiny previously reserved for politicians, may be on the counterattack.

The Sun-Times, which will say little about its investigation, apparently began asking questions about the financial affairs of the 2-million-member archdiocese in the spring. At least four reporters questioned the archdiocese's insurance company, suppliers of goods and services to the archdiocese, relatives of Cardinal John Cody, retired priests, Catholic social service officials and others in what seemed to be a broad look at almost all the church's activities, according to archdiocesan spokesman Peter Foote.

"The inquiries concerning the archdiocese were receiving a significant amount of attention from the people who were being contacted," Foote said. "Since the inquiry went on for an extended period of time, it became the subject of gossip within the church itself."

He was approached by a reporter for the Chicago Catholic, the official paper of the archdiocese, to find out what the Sun-Times was doing, Foote said, and he told the reporter everything he knew about the interviews.

On Aug. 2, the Chicago Catholic published a front-page article describing what it called questionable reporting techniques by the Sun-Times and quoting Foote at length."The questions impung the administrative ability of the archdiocese or of Catholic organizations which raise funds for mission or youth work. . . There's a lot of innuendo in the questions."

Besides the article, the Chicago Catholic ran a heated editorial. "The Chicago Sun-Times appears to see circulation profit in anti-Catholicism," it said. "The hostility of the Sun-Times toward the Catholic Church threatens the right of Catholics to worship as they choose and to conduct their religious affairs as they choose. . . The Chicago Sun-Times is engaged in a program of clandestine character assassination that perhaps would win the endorsement of the Ku Klux Klan."

The archdiocesan paper called on the Sun-Times to respond, and in a letter published Aug. 29 in the Chicago Catholic, editor Otwell stated that "in the course of their normal duties, reporters pursue many lines of inquiry, some productive, some not. Such news-gathering efforts should not be prejudged on the basis of 'apprehension' but on the fairness and accuracy of what is published."

In an interview, Otwell said that except for the articles and editorial in the Chicago Catholic, which in turn produced a flow of pro-and-con mail to the paper, there has been no attempt by the archdiocese to pressure the Sun-Times. He said such pressure would not dissuade his paper from publishing an article, should one materialize.

The new inclination of the media to investigate church organizations is illustrated by the fact that the Gannett News Service, which won a Pulitizer Prize for last year's investigation of the Pauline fathers, is also investigating the financial affairs of the Chicago archdiocese, according to Gannett editor William F. Schmick III.

James M. Wall, editor of the Chicago-based Christian Century, said that the investigation of the Chicago archdiocese is one of the few inquiries into mainline religious organizations. But even reporting of internal conflicts within churches, something the Century specializes in, often brings strong reaction. "You may be sure it's something that church people are not accustomed to," he said. Like universities and corporations subjected to private scrutiny, "they very much resent it. They are used to conducting their affairs within the family."