Parishioners of a troubled Roman Catholic parish in Reston have been barred by higher church officials from taking part in funeral rites today for a beloved former pastor.

The exclusion of members of the Church of St. Thomas a Becket from any significant role in the funeral for the Rev. Harris Findlay is expected to fuel a year-long squabble between the parish and Bishop Thomas J. Welsh of Arlington.

Findlay, who died Saturday, served the Reston parish for more than eight years and was, by all accounts, deeply loved and respected. Although he was transferred, because of serious health problems, to the less demanding role of associate pastor of St. Michael's Church in Annandale in 1978, he asked in his will that his funeral be held in the Reston church.

"The parishioners [of St. Thomas] tried very hard to get involved in the planning for the funeral," said Carol Even, a member of the parish. In particular, she said, they tried to get permission for a church member to deliver a eulogy and choir members offered to provide music that they knew the priest had loved.

But request were turned down.

Instead, Bishop Welsh will celebrate the funeral mass, and the music will be provided by a paid organist and congregational singing.

"Father [Findlay] was a man who was unusually beloved by his parish and we are not able to show it," complianed Even, who was once a member of the parish's defunct liturgical committee.

Welsh's official spokesman, Francis McInerney, daid that "the normal rules of the [Catholic] church are being followed" in the planning of the funeral mass. "We're trying just to give him a dignified funeral . . . in the hope that it would be healing" of the divisions in the parish.

The prolonged dispute centers on how much of a role lay members can have in church affairs, said former parish board president David Bobzien. "We have known what it is to have a really having a say in the parish." [parish] board of lay people that were They no longer have such a voice, he said.

But the funeral plans, rather than helping to heal the divisions, were widening them. "This is his [Findlay's] home," church member Carol Dick said yesterday. "The fact that none of us is alllowed to participate is terrible."

Church members were particularly sensitive over plans for the priest's funeral because his tenure was an especially meaningful time for many of them.

"We feel that this community was unique; we feel this community was very special," said Barbara Ewalt.

"You could feel the spirit of love amongst the people," she continued. "You know how Washington is -- everybody is away from their family. But here, we felt like you were involved, like you were home."

Under Findlay's tenure, the parish had an active and involved parish board of lay members, who shouldered much of the responsibility for the parish. b

Although Findlay, as pastor, could override any of the board's actions, he did so only once.

"Father respected the board," said Ewalt, who was a member of it. "I know he felt it gave him time to be a priest. Why should he be involved in how the chairs should be set up or how the parking lot was lit?"

Findley became seriously ill in March 1978.To fill in for him while he was in the hospital, Welsh assigned a retired Air Force chaplain, the Rev. Bernard M. Delos, to the church.

Delos was eventually made pasotr of the church when Findlay's health failed to improve enough for him to carry out eh responsibilities of the parish.

But Delos was not comfortable with the parish board. Early last year a dispute arose over the church's director of religous education, Richard Lawless, whom the board supported. After several months of disagreement between the board and Delos over Lawless' ideas and performance, the educator left. Lawless is now vicar of religious education for the Diocese of Syracuse, one of the few lay persons in the Catholic church to hold such a job.

The dispute over Lawless was magnified in the regularly scheduled elections to the parish board, scheduled for the end of February and first of March last year. An anonymous letter from "Concerned Catholics of St. Thomas a Becket Parish" assailed board members, charging that "under existing board direction, the pastor cannot effectively guide the religious programs" of the church.

Jim Marshall, the parish board president , sought to counter with his own letter to church members defending the board. After 200 copies of the letters were sent to the 1,500-family parish, Delos conficated the rest of them and called off the election.

The problems at St. Thomas were further complicated by the establishment of a second Catholic parish in Reston, St. John Neuman. Although the lay leaders of St. Thomas knew that a new church was inevitable with the growing Catholic population in the area, they had hoped to preserve the spirit and community feeling of St. Thomas.

"Our dream had been that there could be one Reston Catholic community, with one pastor but with assistants serving under him in the two branches," Ewalt explained.

That dream disintegrated when church members read in their diocesan weekly that Welsh had established the new parish.

Reston Catholics, however, are still trying to sustain thee spirit of community and they say they knew under Findlay's leadeship. Last month a group headed by the leaders of St. Thomas' defunct parish board filed articles of incorporation with the State of Virginia for something called the Friends of the Reston Catholic Community, which will embrace members of both parishes.

As it turned out, their first meeting last Sunday became a memorial service for the priest who had made their faith so vital for them.