The Vatican is asking members of Good Shepherd Roman Catholic Parish in Alexandria who have been at odds with their bishop over the role of lay persons in church affairs to go back and make "every effort" to reconcile differences.

The mild admonition from the Vaticans Sacred Congregation of the Clergy was transmitted earlier this week by Bishop Thomas J. Walsh of Arlington to the group that calls itself Good Shepherd Catholics for Shared Responsibility.

The bishop and the GSCSR, a group of some 200-plus parish families who are fighting to retain church reforms authorized by a previous bishop, have been at odds for more than three years.

The Vatisan agreed more than a year ago to try to help resolve the dispute, a step virtually unprecedented in the hierarchical church in which, as Catholic lore has it, "a bishop is God in his own diocese."

Even while both parties to the dispute have reflected a willingness to try once again to resolve their differences, the communication from the Vatican, or more precisely the way it was trasmitted to parishoners, apparently raised fresh problem.

The Vatican, after studying documents submitted by both sides as well as the report of Bishop Joseph Hodges, who had been appointed as apostolic vistator, or Vatican fact-finder, submitted its conclusions in a letter to Bishop Welsh. No copies were sent to the parishoners.

In a letter to Regis Reynolds, current president of GSCSR, the bishop quoted three paragraphs for the Vatican letter from the American prelate, John Cardinal Wright, who heads the Vatican Congregation for the Clergy.

Bishop Welsh has refused to make the entire letter available, on the grounds that "it is a personal letter, it had personal passages in it," according to Leonard Reed, diocesan public relations officer. Reed said yesterday he himself has not been permitted to see the Wright letter.

Reynolds expressed dismay over this refusal. "What kind of a dialogue is it where one guy knows all the facts of the decision and the other one doesn't?" he complained. Nevertheless, he wrote Bishop Welsh that "we look forward to a meeting with you to establish an agenda" for further discussion.

In that part of the Wright letter made available by Bishop Welsh, the Vatican official said the dissenting parishoners "appear to be the minority" within the parish.

Cardinal Wright wrote: "Since the issue at stake is not only the controversy between the bishop and the petitioners, but especially one of resorting parish unity, because all of the parishoners are affected directly or indirectly; taking into consideration the many other facets of the case which would damage not only the church of Arlington but may have an effect on the church in the entire nation, this Sacred Congregation is asking the petitioners to join with the bishop and pastor, making every effort to cooperate in the work of the church according to church policies."

Persons familiar with the style of Vatican communications have speculated that the tone of these passages indicate the letter may also include some criticism of Bishop Welsh in the "personal" passages he has refused to disclose.

Bishop Welsh holds to a conservative, by-the-book style of churchmanship. Prodded by a pastor who has since returned to the Diocese of Richmond, the Good Shepherd parishoness had built an active parish around the leadership and active participation of lay members, citing the reforms called for by the Second Vatican Council.

In the wake of three years of conflict, the parish has lost half its membership.

The dissidents, organized into the GSCSR, have not withdrawn from the church but they do gather regularly for the contemporary liturgies they favor, meeting in an Episcopal Church in Oxon Hill. They have also organized for an active program of social service.