In 1977, when less M than 200 Mormon faithful first congregated in this small town on the rural fringe of Washington, they met in an old schoolhouse that had no heat in the winter and was sweltering in the summer. But the Mormons prospered in the next four years, their congregation growing to over 300, and they longed for a real church in which to worship and enrich the athletic and social lives of their children.

The result is an elaborate $1 million meeting house that will open in November on farmland north of Mount Airy -- and some attention church leaders feel they could have done without.

Concerned, they said, with the "eternal souls" of their neighbors, five local ministers of various denominations sent out some 4,300 letters warning residents not to be misled by the doctrine of the Church of Jesus Christ of Latter-day Saints.

"If the Mormons were just another Christian denomination there would be no need for this letter," said the ministers, who said they represented "the concerned churches of Mount Airy" and enclosed a packet of religious material to illustrate their position. "BUT THEY ARE NOT! MORMONISM IS NOT CHRISTIANITY! Please read the enclosed material and see for yourself . . . Your eternal life is worth it."

The five ministers stressed that they meant the letter to be "informative" only. But their statements have greatly dismayed area Mormons, and have come under attack from a local newspaper for being "one-sided and unfair." And so a theological debate is raging in this unlikely setting.

"I'd have to ask myself how they would react if a Jewish synagogue decided to move here," said Mount Airy Mormon Bishop John E. Abernathy. "Between the five of them are differences in doctrine. We feel we have the truth and allow them the same privilege."

But the ministers defend their action, saying it was based on telling the whole truth about Mormon religion. "People have been calling various pastors, wanting to know if the Mormons were Christian in theology," said the Rev. Wallace Lusk of the Mount Airy Full Gospel Church. Lusk, who signed the letter, added "The Mormons don't follow Judeo-Christian background. It sounds like it has a Christian flavor, but it isn't."

"It is not a Christian religion. There are large differences with what they believe," said the Rev. David N. Wentz, pastor of the Prospect United Methodist Church.

"We are absolutely a Christ-centered religion," countered Ralph Hardy, a lawyer and a Mormon spokesman. The five ministers "just aren't acquainted with the facts. We believe in the Bible as the Way of God. Christ is at the very heart of our lives and our religion," he said.

There are 35,000 followers of the Church of Jesus Christ of Latter-day Saints in the Washington area and more than 4.6 million worldwide. The suggestion that the Mormon faith is not Christian is a sensitive ideological charge that has gone on since the religion began in the 1800s and led to the violent death of its principal prophet, Joseph Smith.

"It is a rather touchy thing to discuss . . . It's God's job to judge, not ours," said Peggy Shriver, head of Research Evaluation and Planning for the National Council of Churches in New York City.

Still, the five Mount Airy ministers feel they know the answer, focusing on Mormon practices such as baptism for the dead, and their idea that Mormons believe in more than one true God.

"If people believe in straight Mormon doctrine, then they are lost," said Pastor Irvin S. Martin, adding that he believed the Mormon faith was based on good works on earth, but not on faith. "You don't get to heaven from good works," said the Rev. Wallace Lusk.

Some Mount Airy residents openly question whether the packets were prompted by jealousy over the Mormons' new meeting house, which will include enough room for two congregations, a library, classrooms and a gymnasium that will double as a stage area for community programs. Others cited fears that the Mormons would deplete the congregations of local churches.

"The reason we mailed this out is that they are building a church and concentrating on door-to-door efforts. They are not up front about their basic beliefs," said Wentz. "In common with many other cults, they use the same words as Christianity but attach different meaning to them."

But Abernathy, the Mormon bishop for the area that extends from Mount Airy and Damascus to New Market, said that most of their members do not come from door-to-door proselytizing, but from friends of current followers. Currently, there are only two missionaries, Mormon men aged 19 to 21 who devote two years of their lives to spreading the Mormon faith, operating in the Mount Airy area, said Abernathy.

"I think some of the ministers were fearful that we might take some of their members," Abernathy said. "From what I have seen most people have not supported their actions."

"Maybe the letter could have been formulated differently," said Lusk. "But if I really felt my neighbor's eternal destiny was in the balance, I'd do it again."