The nation's first deaf Roman Catholic priest was ordained here today. The event was of immense significance to thousands of deaf Catholics who for years have sought acknowledgement of their silent community whithin the church.

"We are deeply conscious that this is a historic moment for the United States, Baltimore and this cathedral," Lawrence Cardinal Shehan, former archbishop of Baltimore, told Thomas Coughlin, before ordaining him a Trinitarian priest at the Basilica of the Assumption in front of 500 mostly deaf friends and relatives. The 90-minute ceremony was offered in both words and sign language.

The church has been "a foreign place" for the deaf, Coughlin said in an interview last week. "They have never had a deaf priest who could speak their language, who feels the same way they do . . ."

The path to the priesthood is not a clear one for the deaf, either. There has been a religious stereotype in the way: the priest as perfect physical specimen chosen by God as model. There was, for Coughlin, a painful isolation while studying for the priesthood, the only deaf man among the hearing.

Finally, there was gnawing self-doubt about the sacrifice of celibacy. "The deaf person has a greater sense of loneliness and is most likely to have a partner, to be married," Coughlin said. "I will need people. The celibacy will bother me if I have no community."

Coughlin a graduate of Gallaudet College, wears a small sound amplifier behind his ear with a thin cord running ro a tiny battery pack under his breast pocket. It allows him to hear vowels through auditory vibrations. He cannot hear consonants. Nevertheless, he had learned to speak, with the aid of sign language and, occasionally, a pad and pencil.

He is a gregarious person who has overcome what he calls large "ego problems" to pursue of priesthood. Now he sees himself as a bridge between his own deaf subculture and the hearing world.

"In general," he said, "a deaf person has an ambiguous concept of God" and tends to stay away from the church because "it's too abstract for them." They often have difficulty acquiring meanings that hearing persons obtain through the spoken language.

If anyone is equipped to undertake this uncharted priestly task, it is Coughlin, according to those who have helped train him. "He's got everything.He's intelligent, personable and he's a man of zeal. He really feels a responsibility for the church's work with the hearing impaired," said the Rev. Dave Walsh, who directs the National Catholic Office for the Deaf, which we opened at Trinity College in Washington in January 1976.

"He's a real Helen Keller," said the Rev. Joseph Lupo, vocations director for the Trinitarian order in Pikesville, Md., and the man urged Coughlin to pursue his clerical training in spite of his many temptations to quit.

Coughlin was born in Malone, N.Y., of deaf parents and deaf material grandparents. He has three sisters who are not deaf. Coughlin was sent at a preschool age to the Rochester School for the Deaf, and graduated from St. Mary's School, a secondary institution for the deaf run by the Sisters of St. Joseph, in Buffalo in 1967. After receiving a bachelor's degree in English from Gallaudet in 1972, he joined the Trinitarians a few months later.

A year ago he recieved a master's degree in theology from Catholic University, and he is completing special courses at Gagllaudet - in family counseling and the dynamics of adjustment to deafness.

The chaplain at St. Mary's was Coughlin's inspiration into the priesthood. But when he applied to the Carmelite order, he was turned down by letter "because they could not see how I would function" in holy communion and other duties nor "get along" with the religious community.

"I felt very small when I got that letter," he recalled. "I felt I was misunderstood."

He began corresponding with Father Lupo and eventually the priest asked Coughlin to tell him more about himself. "I said I was an ordinary American deaf boy," Coughlin said. The next letter he received from Lupo listed all the difficulties the future priest could face, "but he said he would leave the door slightly open for me."

"I went down to visit them and I think they were surprise that I was not mute and dumb. They did not have a proper understanding of a deaf person, and they didn't know what to do with one," he said.

While studying for the priesthood as the only man among the hearing, Coughlin said he felt "very isolated, like I was in a foreign land. "I wanted to leave many times. I was upset."

Before he went to the Trinitarians, he did not speak well, he said. "I did not have to use my speech, But why fellow classmates said, how do we communicate with you? They forced me to speak," and a few learned sign language.

Still, it was a lonely course, with no one really to talk in depth about his theological studies, his sole focus for four years. So much of community life is built around the casual conversations, the shouts up and down the hall of the residence, the prayer life and the recreation. In all, he was left out.

At dinner when the students would return home after a busy day with a lot to say to each other. "We would be eating and talking at the same time," said Brother Tom Serullo, a Trinitarian. "Sometimes he would pick up what we were saying because of the expression on our faces and he would get in on some aspects of the conversation." Even for a man who reads lips expertly, that is not enough.

For his four years at Catholic University, Coughlin had to hire an interpreter, Irene Steckel, at $10 an hour (which was paid for by government funds and the Trinitarians). A teletype machine was installed at his residence. It enables the deaf to communicate with each other and costs $600.

In his new job, Coughlin will assists the Rev. Rudy Gawlik, who will become the director for the program for the deaf in the Archdiocese of Baltimore in July. Much of Coughlin's time will be spent traveling to work among the approximately 95,000 deaf Catholics in the United States.

After 100 priests around the nation minister to the hearing impared, but only 37 of them are in full-time work. Father Walsh said there are 147 sisters in Catholic schools for deaf and about 70 others involved in parish work. About a half dozen nuns in the U.S. are deaf.

"In the past," Coughlin said somewhat hesistantly, "it was easy for me to idolize others, but now everything for me is real. I am going to open up a new world for the deaf. They are just as good as anyone else - different maybe - but beautiful people. I don't know how I made it through. It must be the work of God."

Among those attending the ceremony today was Ray Fleming, also deaf, who will be soon ordained a Franciscan. Two other Catholic priests in the world, one in South America and one in South Africa, have been deaf since birth.

The uniqueness of the silent world was acknowledged throughout the ritual. A Bible reading declared that "We are all different, yet we depend on each other. We all have different gifts that God has given us."

Throughout the ritual, which ended with the traditional "laying on of hands," many in the crowd wept openly," including Coughlin's family. When the ritual ended, the new priest walked over to embrace his sobbing mother and grandmother, who are deaf, and his three sisters, who are not.