Five years ago, Esperanza Hincapie had sunk into a pit of despondency. With a daughter in prison for murder, she contemplated swallowing a mouthful of pills to blot out her heartache. Then four Hispanic ladies from Rebano Companerismo Cristiano--a Pentecostal church in the Humboldt Park area of Chicago--came to visit her. They encircled Hincapie--a lifelong Roman Catholic from Colombia--laid hands on her and prayed. "I felt a tremendous chill," she recalls. "I began to cry and cry, and released everything." The following Sunday, one of the women drove her to Rebano, where Hincapie, 52, converted and permanently joined the flock. At her Catholic church, she says, "I always left feeling empty." At her new one, "I felt something beautiful--the presence of the Lord."

It was another successful conversion for Rebano, one of dozens of churches--including Lutheran, Jehovah's Witness and Seventh-day Adventist--that crowd the gritty streets of Hispanic-rich Humboldt Park and vie for Latino souls. Their ground battle offers a granular view of a broader struggle taking place nationwide. Forty million strong and deeply religious, Hispanics are traditionally Catholic. But, research shows, the longer they are in the United States, the more open they are to other faiths. While 72 percent of first-generation Hispanics are Catholic, according to one study, that figure drops to 52 percent by the third generation--a trend that has long troubled the Catholic hierarchy. Latinos remain the Catholic church's fastest-growing ethnic bloc, but they are also one of the fastest-growing segments among Mormons, Methodists and most other denominations. The result: all faiths are courting Hispanics with a marketing savvy more often associated with corporate America. These churches "have plans to grow, and they're aggressive," says Edwin Hernandez of the University of Notre Dame. "The competition is rampant."

That's especially true among Pentecostals. With their cathartic, music-filled worship style and aggressive proselytizing, they've made deep inroads in Hispanic communities. Of the 610 Latino churches that Hernandez and a research team have mapped in Chicago (as part of an ongoing study of how the churches attract and retain congregants), 202 are Pentecostal, compared with 119 that are Roman Catholic, though the latter are much bigger on average. In Humboldt Park-- a neighborhood filled with Puerto Ricans, Mexicans and Central Americans--Pentecostal churches abound in rich variety, from storefront outfits with strict codes governing dress and behavior, to warehouse operations with more lenient approaches. While the leaders tolerate one another, rivalries simmer close to the surface. From her perch at the tiny Iglesia de Dios Peniel, Pastor America Garcia eyes Rebano down the street--where female congregants might sport tight pants and belly rings--with suspicion. The place is rife with "libertinism," she says. "When people leave, they go to orgies, to movies, to dances!" Rebano's Lynette Santiago has heard all this before. Back when her parents led the congregation and replaced old-school coritos, or spiritual songs, with a salsa band, a disapproving pastor labeled her mother "the Devil."

Santiago and her husband are now focused on attracting a younger generation to replace the old guard that left when her parents ceded the reins. The couple has abandoned traditional evangelism--wielding a bullhorn and a fistful of tracts on a street corner--in favor of M.B.A.-caliber marketing. Drawing on materials from Outreach, a marketing firm aimed at white evangelical churches, they've experimented with a variety of growth strategies--direct mail sent to Latino addresses culled from consumer databases; a "40 Dias con Proposito" ("40 Days of Purpose") campaign inspired by Rick Warren's "The Purpose-Driven Life." Above all, they offer an inviting sanctuary with amenities for all, like a new youth center stocked with games and computers. "People are looking for service," says Santiago's husband, Freddy. "It's like a business." Membership has increased from 625 two years ago to 900 today.

In the religious marketplace of Humboldt Park, the fastest-growing churches are the ones that have engaged the surrounding community. New Life Covenant, an Assemblies of God congregation, swelled from 125 to 1,700 members in four years after Wilfredo De Jesus took over as senior pastor. With entrepreneurial zeal he created 70 ministries for every conceivable niche group and enacted Biblical stories with live animals such as a camel and a 500-pound pig. The church also started men's and women's shelters and a farm outside Chicago for drug addicts and prostitutes. "We started to just go after people who were wounded and hurting," says Associate Pastor Rico Altiery. To fund these projects, the church has relied on a combination of tithes--which have ballooned in tandem with the congregation--large individual donations and public grants.

At nearby St. Mark's Catholic Church, the deacon, Antonio Navarro, has watched with dismay as his Latino congregation has shrunk steadily over the years, partly due to defections to other faiths. "Sometimes they don't see the value of what they received here," he laments. The church has staunched some of the bleeding with a charismatic group that offers a worship style akin to that of the Pentecostals. But Catholics will never match the aggressive evangelism of rival churches. "We keep trying to imitate the Protestants, but it doesn't work," says Richard Simon, Cardinal Francis George's liaison for charismatic renewal. Just ask Esperanza Hincapie, whose jailed daughter abandoned the Catholic church two years ago. A prison ministry sponsored by an evangelical church converted her.