They question the wisdom of placing less emphasis on a tenet that has defined Pentecostalism for more than a century.
"It's different now," Walters said. "People don't like to stand out if they don't have to."
As the religion becomes more widely accepted, Walters said, there has been a tendency for large Pentecostal churches to downplay the differences between Pentecostalism and other well-known Christian denominations.
The Assemblies of God, one of the nation's largest Pentecostal denominations with 3 million members, has 66 million members worldwide. Assemblies officials worried about the decline in messages in tongues or spirit baptism at a general council meeting this month. The practice decreased by about 3 percent to fewer than 82,000, the lowest total since 1995, according to statistics released by the Assemblies of God.
"This is a long-developing phenomenon," said Harvey Cox, an expert in Pentecostalism and professor of religion at the Harvard Divinity School. "They don't want what appears to be objectionable to stick out or be viewed with suspicion."
Meanwhile, newer strands of Pentecostalism often with roots in other countries like Nigeria and El Salvador continue to emphasize the practice in church as well as in personal prayer, Cox said.
While all Pentecostals accept speaking in tongues as a "gift of the Holy Spirit," these smaller, niche congregations aren't afraid to embrace the practice and don't care whether it scares some away, he said.
Pentecostalism represents one of the fastest-growing segments of global Christianity. At least a quarter of the world's 2 billion Christians are members of the Pentecostal faith or related charismatic movements, according to the Pew Research Center.
For the first decade, the movement was mainly comprised of poor white and African-American worshippers. Influenced by the spiritual renewal of the Azusa Street Revival a Pentecostal revival meeting that took place in Los Angeles in 1906 the Assemblies grew with interracial services that included speaking in tongues, prophecy and faith healing.
Occasionally, parishioners were "slain in the Spirit," falling to the floor following an encounter with the Holy Spirit.
Pentecostals believe speaking in tongues may be an unlearned human language as the Bible claims happened on the Day of Pentecost or it may be the language of angels. Studies show that words spoken when delivering messages in tongues lack the components and patterns of a true language.
At his service in a small chapel in the West Valley Christian Center, Walters steps aside after reading scripture and introduces a guest: Nick Farone, a pastor who runs a Christian center in Louisiana.
A member of the Pentecostal Church Of God a denomination with about 500,000 members Farone uses his time on stage to preach returning to the basics of the faith. Parishioners in the pews nod their heads in agreement, swaying back and forth.
"Praise Jesus," a woman says, her eyes closed and head bowed.
Farone said many Pentecostal pastors are failing to stress the importance of messages in tongues in their teachings.
The emotional and spiritual connection of speaking in tongues, the visceral experience, is what appeals to those in need during a time of economic and social instability, and is arguably the heart of the Pentecostal movement, he said.
After the service, Farone placed his right hand on his forehead and began to speak again. This time, the words were impossible to understand, streaming out in a long, rambling string of sound. He had just spoken in tongues, he said later.
"This is our power," he added, acknowledging he was unsure of what he had just said. "We shouldn't be ashamed."
The success of smaller congregations in Latin America and Africa is linked to their openness to the supernatural experience, Farone said. Poor parishioners feel they can contribute to the congregation by interpreting the word of God, despite living in hardship.
"You can't preach wealth in these places," he said. "Smaller churches have bigger hearts."
Adrian Tigmo has been attending service at Three Crosses for more than 20 years. The 64-year-old said he believes messages in tongues have declined because people outside the faith have been critical of the practice.
While he prays in tongues during worship, he does so quietly and to himself not aloud for the congregation to hear.
For him, the resurgence of speaking in tongues in church depends on people leading by example. He said, "People can't just give up."
Follow Sarah Parvini on Twitter at http://www.twitter.com/parviniparlance