Like hundreds of area Catholic priests who climbed into their pulpits during Sunday Mass yesterday, Monsignor Thomas P. Scannell faced a congregation confused and curious about the American bishops' controversial and historic pastoral letter condemning nuclear weapons.

Unlike some of his colleagues, who declined as one priest said to mix "missiles and Moms" in yesterday's homilies, Scannell, 72, of St. Michael's Catholic Church in Annandale, tackled the controversy, but without specifically mentioning the letter.

"Who writes the ticket?" Scannell asked his congregation as he stood under the church's brilliant stained-glass dome. "That is the central question. What person is it who says 'This is God's law?' . . . . When you're troubled, uneasy, distressed, angry about difference of opinion, one priest saying this, another that, even some of our hierarchy propose this or that. When you hear this, bear this in mind. There's only one spokesman for Jesus Christ in the world. . . The papacy," Scannell said. "The answer must come from that source."

The bishops' letter last week became the official basis for Catholic Church teaching in this country when it was adopted in Chicago after more than two years of debate. It calls for a halt to the testing, production and deployment of new nuclear weapons, placing the American Catholic Church at odds with U.S. nuclear policy.

The 150-page letter has divided Catholic clergy over the document's impact on workaday Catholics, particularly defense and military personnel who work with nuclear weapons. The letter has been described by some church leaders as guiding but not binding--giving Catholics moral guidance but leaving them with the right to disagree.

Many area priests have not yet seen a full text of the letter, and among those familiar with it there is mixed reaction.

Scannell, whose parish has many military and defense workers, took issue with the letter's detailed pronouncements on nuclear warfare.

"They don't have the expertise in these technical matters, and I don't see where it's going to have one blessed effect," Scannell said as he stood waiting to greet parishioners after Mass. He complained that the bishops have spent too much time discussing nuclear weapons when "half the morality has gone down the drain and youth and education problems are tearing the guts out of this country."

In Alexandria, at the Good Shepherd Catholic Church, the Rev. Gerard Creedon made the letter, which he supports, a part of Sunday services. "We prayed that the church would be responsive to the leadership of the bishops," said Creedon, interviewed by telephone. His parish, he said, has mixed feelings about the letter. "Very few have read the entire text."

The concern over nuclear war, Creedon said, is very much a part of the church's mission. "This kind of issue and discussion is as germane to Christ's followers as worship. For priests to dilute the mission of the church and focus only on individuals is to miss the drift of the church's mission."

At St. Anthony's Catholic Church in Northeast Washington, the Rev. Michael Blackwell said he did not mention the letter at Sunday services, "it being Mother's Day. That's a tough mix, missiles and Moms."

"I don't know if I would use the pulpit," to discuss the letter, said Monsignor William T. Reinecke of Fairfax County's St. Ambrose Church. "We have lots of retired Navy captains and colonels in this area. It's a big thing to them. You have to be a little prudent. I wouldn't want to tackle it without having studied it carefully."

And at St. Vincent de Paul Church in Southeast Washington, the Rev. John Carroll, "pastor and handyman" described the letter as "not exactly pertinent to my situation. We're an inner-city parish. We're into more elementary things, such as paying the rent. But I don't think it's wrong to be discussing it and thinking about it." Yesterday morning, parishioners at St. Michael's agreed there is nothing wrong with disucussing the nuclear arms question. But they expressed doubts that the bishops' letter, controversial or not, would affect their daily lives.

"I don't think it's binding because it's not the pope's teaching," said a Pentagon computer designer who, like many other parishioners, declined to give him name. "To me, it's still a very simple thing. You're not supposed to kill but you're allowed to defend yourself."

Another Pentagon employe said he thought the church needed to "take a position" on nuclear weapons. "Everyone needs to be concerned. But I don't think you could possibly consider it binding, because of the separation of church and state."

"Well, I think it's wonderful," said Cora Gordon, 80. "After all, if they use them you know we're all going to be destroyed." Defense workers, Gordon said, must do their jobs, "although I don't think they like to do it."

"They were trying to nudge Ronald Reagan into taking arms control seriously. That's what motivated these people," said another parishioner, a government printing office employe. "That can't be all bad."