As a Baptist preacher in Waco, Tex., the Rev. Randall O'Brien knows that the Bible says natural disasters can be signs of God's judgment. But he's not preaching anything of the sort, not even in a year marked by earthquakes, floods and hurricanes.

Instead, he's joining other evangelical Protestant leaders in offering an answer that would have been almost unthinkable for a Bible-believing preacher even one generation ago. Despite all he knows from Scripture, O'Brien is proclaiming God to be a mystery, at least when calamity occurs.

"I don't know why bad things happen to innocent people," said O'Brien, interim pastor at Columbus Avenue Baptist Church and chairman of the religion department at Baylor University. "There's something very worshipful about saying that God is God, and I'm not."

O'Brien illustrates a growing admittance of puzzlement in evangelical circles. That has prompted some religion scholars to wonder if understandings of God -- and religious authority -- might be undergoing subtle but significant revisions among one of the country's largest and most influential religious groups.

Across the nation, evangelical leaders are finding themselves challenged to explain what insurers eerily call "acts of God." Sunday sermons reflect on hurricanes in Louisiana, mudslides in Guatemala, floods in New England, an epic earthquake in Pakistan and even heavy rains in Washington that scared crowds away from the Mall during an evangelistic rally.

Evangelicalism "is a movement that vests people with authority when they can convince [others] that they have something strong and powerful and effective to say," said Joel Carpenter, provost of Calvin College in Grand Rapids, Mich., and a historian of American religion.

"So, yeah, you're giving up something when you say, 'Look, folks, this is just mysterious. And yes, as a careful student of the Scripture, I search and search, and I find the biblical writer is pointing to mystery as well, pointing to trust as the answer, [rather than] relying on my own understanding."'

For at least 250 years, Carpenter said, evangelicals have placed a premium on understanding matters of God as a crucial sign of an individual's salvation. Carpenter said anyone unsure of personal righteousness, especially in the 18th and 19th centuries, probably would hear from an evangelist: "If you can't be more certain than that, then maybe you ought to doubt your salvation, and you can settle that today" by surrendering to Jesus Christ.

The point, Carpenter said, was that "God really is going to make things clear to you, all kinds of things."

Through the decades, scholars say, this notion of the saved as knowledgeable in all things godly has allowed little room for divine mystery. But evangelical leaders today are increasingly admitting a lack of answers. Evangelist Luis Palau, for instance, offered no explanation for why God allowed heavy rain to hinder his DC Festival last month, an event that carried high expectations after years of planning.

"You either believe that God is sovereign, that he makes no mistakes, that his way is perfect, as the Bible says, or you don't," Palau told a drenched and diminished crowd on the Mall. "And I believe it."

On the festival's final day, the sun came out, helping to attract 50,000 people. Still, the rain so perplexed Washington area evangelicals that a Christian radio station devoted a call-in talk show to the subject. Many callers admitted that they didn't know why a good God would allow bad weather to hamper a noble cause.

Palau isn't the only high-profile evangelical scratching his head over the weather.

On Oct. 21, the Rev. Jerry Falwell wrote in his newsletter, "Falwell Confidential": "What is the biblical significance of all these global disasters which have befallen us recently? The honest answer is, I do not know."

Falwell's open befuddlement is a shift for a Southern Baptist preacher who infamously said the Sept. 11, 2001, attacks were divine judgment for "throwing God out of the public square."

Perhaps the days are fading, Carpenter suggested, when evangelicals "think they have power to convince and persuade [only] as long as they have power to explain."

As they ponder life's uncertainty in a post-Sept. 11, disaster-prone world, evangelical leaders are daring to speak of mystery even beyond the weather.

"All evangelical leaders today are dealing with much more sophisticated clienteles and are themselves theologically more nuanced" than in decades past, said David Edwin Harrell, professor emeritus of history at Auburn University in Alabama and an expert on evangelical leaders of the 20th century.

That has prompted the faithful to either rethink their beliefs or embrace the mystery of a loving God who somehow allows the innocent to suffer, said Richard J. Mouw, president of Fuller Theological Seminary, a training ground for evangelical pastors in Pasadena, Calif.

"There's an embarrassment over the glibness of the past in which some of our leaders were so sure, you know, why 9/11 hit or so sure New Orleans got it because of its decadence and lifestyle," Mouw said. "In many ways these leaders, in order to really have the respect of the rank and file, need to not sound so glib and sound wiser in their willingness to encourage people to live with the mystery."

But, he predicted, some adherents will grow uneasy with the burgeoning evangelical affair with wonder.

"Insofar as the attraction of evangelicalism is that we've provided easy answers and allowed people to feel very comfortable in a universe where they have things pretty well figured out," he said, "it takes a much more mature faith [to live with mystery], and fewer probably will be able to handle it."

Evangelical preachers who once might have cited New Orleans's decadence as the reason for its fate would now be seen as glib and provoke embarrassment, a seminary leader says. Evangelist Luis Palau offered no explanation for why God would allow rain to hinder his DC Festival last month on the Mall.