UNITED STATES - August 25: Delfino Velazquez holds his rosary beads as he prays with about 200 people who gathered for an emotional prayer vigil at Saint Paul Catholic Church in Allentown Pennsylvania, targeting Rep. Charlie Dent, R-PA., and Rep. Joe Pitts, R-PA., over immigration issues. Congressmen Dent and Pitts where both invited but neither showed up at the event that was sponsored by Congregations United for Neighborhood Action (CUNA). (Photo By Douglas Graham/CQ Roll Call)

While immigration over several decades has driven up the share of Hispanics in the pews across U.S. Catholic churches, a new survey shows that Hispanic Americans are also quickly leaving the church for Protestantism or choosing not to identify with any particular religion at all.

The Pew Research Center's survey on religion among Hispanic Americans, released Wednesday, found that nearly one-in-four Hispanics are now former Catholics, and predicted that "a day could come when a majority of Catholics in the United States will be Hispanic, even though the majority of Hispanics might no longer be Catholic."

The study reports that 55 percent of Hispanics, or about 19.6 million of the estimated 35.4 million Latinos in the U.S., are Catholic. The number is a sharp decline from four years ago, when Pew's polling found that two-thirds -- 67 percent -- of Hispanics were Catholic. The survey shows an increasing prevalence of Catholics "switching" to Protestant churches, especially evangelical and Pentecostal ones, as well as a rising number of young Hispanics who don't align themselves with any religious group. Today, 22 percent of Hispanics are Protestants and 18 percent are religiously unaffiliated, pollsters found.

Pew analyzed religious differences between age groups as well as between Hispanics who immigrated to the U.S. compared to those who were born in the nation. Among the half of U.S. Hispanics who were born outside the U.S., "Catholics have had a net loss of 19 percentage points due to religious switching," the study reported, with Protestants and the "nones," or religiously unaffiliated, making an equal percentage of gains. Around half of Hispanics whose religion changed since childhood said the change happened after moving to the U.S. Among native-born Hispanics, Pew found that most who changed their religious affiliation went from being Catholic to having no religion.

"Today, fewer than half of Hispanics under age 30 are Catholic (45 percent), compared with about two-thirds of those ages 50 and older (64 percent)," the study's authors wrote. "At the same time, Catholics under age 50 are much more likely to be Hispanic than those ages 50 and older (44 percent vs. 21 percent)."

Still, they added, "Hispanics continue to make up an increasingly large share of U.S. Catholics… As of 2013, one-third (33 percent) of all U.S. Catholics were Hispanic, according to Pew Research surveys."

The dual trends of growing Hispanics in the Catholic church as well as the increased number of Hispanic Catholics who are leaving the church can happen at once because of the growing number of Hispanics living in the U.S. About 16.9 percent of U.S. residents were Hispanic in 2012, compared to 12.5 percent in 2000.