During the day they huddled together, heads bowed and hands joined in prayer, in knots of four or five in hotel lobbies and parking lots all over the city. At night they massed 40,000 strong in the orange and yellow plastic seats of the Kansas City Chiefs football stadium for songs, sermons and praise.

For four days and nights they heard their leaders proclaim their movement to the unstoppable, a new "great awakening," the greatest gathering of Christians in 800 years.

The gathering was that of the charismatics, the strand of Christian expression cutting across all denominations which pollster George Gallup has pinpointed as one of the main-springs of religious renewal in this country.

Ask any of the smiling. Bible-toting Christians here over the weekend why they traveled up to thousands of miles to this first interdenominational assembly of charismatics and the anwer came back almost universally: praise God.!"

Church leaders estimate that there are 10 million charismatics in the United States, one-half of whom have emerged in the last 15 years, and perhaps 50 million worldwide. The movement is characterized by an experience called the "Baptism of the Holy Spirit," in which the believer perceives a personal contact with God through the Holy Spirit.

Although most of the thousands gathered here were veterans of the emotional and ecstatic charismatic experience, one of the workshops offered to demonstrate "How to Receive the Baptism of the Holy Spirit."

The workshop leader, the Rev, Rick Bradford, directed some 120 slightly nervous candidates to the folding chairs in a downtown hotel and explained the procedure.

"First," he said, "I need to be reassured that you are Christians. Can all of you really say that Jesus Christ is your savior and Lord?" Every hand was raised. "Can all of you say that Jesus Christ was raised again from the dead?" Again the hands went up.

"You're already heaven-bound," he observed, citing the biblical text that describes those requirements for salvation. "But you want more power in your life, in your ministry."

First, he said he would line out a prayer which they were to repeat, asking God to remove all fears, doubts, inhibitions and sins, particularly "sins of the occult."

Then Bradford directed the petitioners to "take a step of faith and start praising [God] in a language you never learned . . . just start with sounds, any sounds." A sort of low chant emerged from the front rows.

For a minute or two a soft sibilant chanting sound grew, punctuated by an occasional "thank you jesus." But soon the sound ebbed and Bradford suggested that the group "begin to sing in the Spirit," as the entire convention did periodically during the evening mass meetings at the stadium.

This time a singing sound arose on a single musical note - or a harmonic of it, like a faulty pipe organ. But soom this died away, too.

"You in the back of the room." Bradford requested, "would you begin to sing some familiar song?"

Someone began the familiar charismatic hymn that nightly triggered the speaking in tongues at the stadium. Softly and prayerfully the group ran through several verses, but there were few visible or audible manifestations of the spirit.

"Sometimes the Holy Spirit comes so quietly and beautifully you're not sure you've gotten it," Bradford said. "Some of you have not received all you will experience. My wife received the Baptism of the Spirit about 10:30 one morning with only a few quiet prayers, but about 2:30 the next morning she awakened with a flood of new words."

Afterward, Larry Whittier of Orlando, Fla., said he had experienced "a closer awareness of God."

Asked if she had received the Spirit Baptism. Cindye Davidson of Fairbanks. Alaska, who was still wiping her eyes as she left the room, replied with a faint air of bewilderment, "I must have."

For many the charismatic experience has meant a whole new lifestyle.

Joseph Garcia of Fort Lauderdale, Fla., was a lifelong Catholic, but when his marriage and his business fell apart at the same time, the church he grew up in couldn't help him deal with the despair he felt. He consulted with the "shepherd," the pastor of the charismatic community, and after a long counseling session one night. Garcia received the baptism of the Holy Spirit.

He joined a highly structured charismatic community, the Church of the Good Shepherd, where about 80 dedicated members nurture each other's spiritual growth under the direction of the "shepherd" who exericses authority over every aspect of his parishioners' lives.

For Garcia it has been a life-changing experience, "Marterial things are not that important to me anymore. If it's a choice between material things and the Lord, the Lord will always come first in my life," he said.

A taciturn man, not given to discussing personal matters with strangers, Garcia said under prodding that there have been "lots fo blessings" in his life since he became a charismatic. His furniture business has prospered and the new family he has established is a happy one. "We are committed to each other and committed to the Lord."

Theologians here were unable to agree on a precise definition of their movement.But the description given by the Rev. Dr. Robert Tuttle Jr. of Pasadena, Calif., seemed the most helpful.

The charismatic movement, he said, "is the way a lot of people are trying to survive in a screwed-up world."