Today, it's estimated that nearly one quarter of all the Christians in the world are part of the Pentecostal movement, which emphasizes the power of the Holy Spirit. Kim Lawton has our special report on how far Pentecostals have come in just 100 years.
KIM LAWTON: They were once ridiculed as fanatical holy rollers, but their exuberant style of worship appears to have caught on.
Bishop T. D. JAKES (Preaching): Your God is not passive. Your God is not indifferent. And your God is not weak.
LAWTON: Pentecostals are by far the fastest-growing group in Christianity, with multi-megachurches and leaders who are best-selling authors. JOEL OSTEEN (Preaching): Today I will be taught the word of God.
LAWTON: There may be as many as a half billion Pentecostals around the world, with more joining every day, and the movement is only a century old.
Dr. HARVEY COX Jr. (Professor, Harvard Divinity School): That is phenomenal growth. That's astonishing. In fact, there's very little precedent in all of Christian history for a movement which has grown as rapidly as they have and spread around the world as rapidly.
Bishop KEITH BUTLER (Pastor, Word of Faith Christian Center, Detroit): And those people who were once called holy rollers and other names not so charitable today are mainstream.
LAWTON: The modern movement exploded after a mass revival on Azusa Street in Los Angeles. Gary McGee is professor of Pentecostal studies at the Assemblies of God Theological Seminary in Springfield, Missouri, where a museum at the denominational headquarters documents the history.Dr. GARY MCGEE (Professor of Church History and Pentecostal Studies, Assemblies of God Theological Seminary, Springfield, MO): The Azusa Street revival, with the pictures that you see here, has a special place in the collective memory of world Pentecostalism.
LAWTON: The revival grew out of the Holiness tradition, a 19th-century Protestant movement that stressed the need for personal conversion and a holy lifestyle. Around the turn of the century, some Holiness leaders began teaching that Christians could be baptized in the Holy Spirit. In April 1906, William Seymour, a black Holiness preacher and the son of former slaves, brought this message to Los Angeles. He held prayer meetings in a small house on Bonnie Brae Street, where people began what they called speaking in tongues, a sign, they believed, of being touched by the Holy Spirit. When they outgrew that space, Seymour began holding daily meetings in an abandoned stable turned church on Azusa Street.
Dr. COX: There were men and women, black and white. In fact, someone has once said that Azusa Street in 1906 may have been the most integrated location in the United States.
LAWTON: Word of the revival spread, and people came from around the world to be part of it. Local newspapers reported that a "weird Babel of tongues" was breaking loose. The meetings continued for three years.
Participants saw the revival as a rediscovery of the practices described in the New Testament, beginning on the day of Pentecost 50 days after Easter, when the Book of Acts says the Holy Spirit descended on Jesus' followers with tongues of fire. They also saw it as a fulfillment of Old Testament prophecies, which say in the end times God will pour out his Spirit on both men and women.Dr. MCGEE: The heart of Azusa was about evangelizing the world in the last days before Christ came and the sense at the turn of the 20th century that time was running out. So the Spirit was empowering people to go overseas and preach the gospel.
LAWTON: That evangelistic urgency took the message in numerous directions, building a highly varied movement that includes organized Pentecostal denominations and independent Pentecostal churches small and huge. Pentecostal-style worship has also permeated mainline Protestant and Catholic churches in what is called the Charismatic renewal movement. There are now between 10 and 20 million Pentecostals and Charismatics in this country.
According to the 2006 YEARBOOK OF AMERICAN CHURCHES, two Pentecostal denominations are among the 10 largest church bodies in the U.S.: the predominantly African-American Church of God in Christ, with five and a half million members, and the Assemblies of God, with nearly three million. The YEARBOOK says the Assemblies of God is the fastest-growing denomination in the country.
Experts say in all there are between 400 and 600 million Pentecostals and Charismatics in diverse congregations around the globe. Most are considered part of the broad category of "evangelical." But Pentecostals emphasize the individual experience of the Holy Spirit manifested in "gifts" such as speaking in tongues, healing the sick, casting out demons, and prophesying, and an enthusiastic style of praise and singing that is being adopted even in non-Pentecostal churches.Harvey Cox says the movement has great grassroots appeal.
Dr. COX: If you can stand up as you can in a Pentecostal church and pray even though you're an uneducated person -- you can pray, you can even pray what they call "tongues," which is the prayer of the heart -- it equalizes people. It declericalizes the movement. Anybody can come in and do this. LAWTON: Although racial and gender divisions still exist, experts say Pentecostals and Charismatics have given power to people often marginalized by other churches, such as immigrants and women. The draw is a personal connection to God.
PAULA WHITE (Preaching): I don't know who's been left outside, but God is getting ready to come after you. You've had disappointment, you've had unmet expectations, but I came to tell you it's over. God is getting ready to come visit you right now.
Mr. STRANG: I've lived more than half of the Pentecostal movement, and in my lifetime I've seen enormous changes, because in the early days Pentecostals were very much considered "across the tracks."
J. LEE GRADY (Editor, CHARISMA Magazine): The gospel does empower people, and when they get a hold of what that means, in a sense they are empowered themselves. They move up in society. And they also have a vision for transforming society. And I think a lot of Pentecostals today realize that you can't transform society just from the bottom. You've got to go all the way up through the strata of society. So that is happening.
Bishop BUTLER: So many people initially were folks that would be classified at the bottom of the economic ladder. Today, the Pentecostal movement is comprised of people at the highest echelons of government, education, science, you name it.
LAWTON: This 100th anniversary is providing new opportunities for Pentecostals to assess where they may be headed.
Read more of Kim Lawton's interviews about Pentecostalism with 
