One of the fiercest theological struggles in the 140-year history of the Southern Baptist Convention will come to a head here Tuesday, when more than 30,000 "messengers" elect a president of the nation's largest Protestant denomination.

The campaign pits the incumbent, the Rev. Charles Stanley of Atlanta, a popular television evangelist and leader of the denomination's reigning fundamentalist wing, against the Rev. Winfred Moore of Amarillo, the candidate of moderates trying to recapture the control they lost in 1979.

The infighting has been so intense -- evangelist Billy Graham called it the "work of the devil" -- that some Baptist leaders worry that a schism might develop, with churches associated with the losing faction drifting away.

"This is the worst we've ever had," said Walter Shurden, a Baptist historian and professor of Christianity at Mercer University in Macon, Ga. "It threatens to undo us as a denomination. It is sad. It is silly. It is sinful. But it is very serious."

Others take a less apocalyptic view. "We have a number of problems, but we are not close to splittin' this critter up," said Paige Patterson, a leading fundamentalist and president of the Criswell Center for Biblical Studies in Dallas.

To try to smooth over differences, an association of Baptist state presidents announced the creation of a theologically diverse peace committee today. But the presidents acknowledge that the group, which is to report to next year's convention, will have no impact on Tuesday's showdown.

Baptists believe in the Bible's inerrancy -- that is, all scripture is to be taken literally. But they also believe in "soul competency" -- the right of the individual to interpret scripture as he or she understands it.

These two beliefs have frequently produced clashes, and as the denomination has grown larger, so have the spats.

With 14.3 million members, Southern Baptists are the second-largest religious body in the nation (behind Roman Catholics, with 52 million). From impoverished rural southern roots, the group has evolved with the prosperity of the Sun Belt into an affluent mainline Protestant denomination, with churches in 50 states (three-quarters of them in the South).

The tithes and offerings last year in 36,740 Southern Baptist churches amounted to $3.4 billion, which goes to support six seminaries; hundreds of hospitals, colleges and institutions for the elderly, and nearly 5,000 missions in the United States and 104 other countries.

Fundamentalists came to power in 1979, contending that there was a "liberal drift" within the denomination, in theology and in practice.

They cited the presence of some professors who do not teach seminarians the literal interpretation of the Bible, an increase in the number of congregations ordaining women and the fading of a "Christian atmosphere" on some campuses, such as Baylor University in Texas.

"Yes, we believe in soul competency, but when it comes to preaching and teaching, you've got to accept the basic premise that the Bible is the word of God," said the Rev. Bob Payne of Independence, Mo.

Moderates contend that the theological complaints are overdrawn and are a smokescreen for a power play. To dramatize their point, they have rallied behind a candidate for president, Moore, who would have a hard time donning a "moderate" label in any of the less conservative Protestant denominations.

Moore, president of the autonomous Baptist General Convention of Texas, jokingly decribes himself as being "to the right of the Ayatollah" Ruhollah Khomeini, and says he, like Stanley, believes in the inerrancy of the Bible.

Moderates contend that Stanley and his predecessors have used the appointive powers of the president's office to place fundamentalists on seminary and mission boards. They also contend that the fundamentalists are abandoning Baptists' stand on separation of church and state by joining with the Moral Majority (Stanley was a co-founder) in calling for a return to Christian practices in public places.

In the months leading to the convention, there were accusations about "heresy files" and secret tape-recordings of Bible classes; there have been sharp words and get-out-the-vote letter campaigns reminiscent of a political campaign -- all of which has left a sour taste in the mouths of many messengers.

Under convention procedures, the president is elected by messengers, who represent individual churches (each church is assigned up to 10 messengers, depending on its size and the amount of its contributions to denominational cooperative programs). As of late today, more than 30,000 messengers had registered here, setting a record. Registration was to continue until Tuesday's vote.