"It really required a double take," said the executive, speaking on condition of anonymity because his comments were not authorized by the company. "I looked at it the way you slow down for a car wreck."

Since the 1980s, employers have allowed workers with common interests — including gays and lesbians, military families and people of shared ethnic backgrounds — to form "diversity groups." Some companies say the policy has helped the bottom line: Recruitment, retention and productivity have improved as employees have begun to feel more connected to the workplace.

So when Christians started asking to be included in the trend, many companies saw it as an extension of an idea that already had served them well. Some offered not only access to corporate facilities but also budgets that could run into the thousands of dollars.

General Motors Corp., among others, have refused to recognize religious employee groups, although they allow workers to organize around race, sexual orientation and gender.

"There is a spectrum ranging from proactive corporate leaders who are saying we need to think about this and find appropriate ways to embrace it, and others who say this is a complete hornet's nest," said David W. Miller, executive director of the Yale Center for Faith & Culture. "We are watching corporate America in the throes of this. It's the great laboratory."

The push for religious expression is coming from people of many faiths but primarily from evangelical Christians.

"My faith is part of me," says Jim Sabia, 33, a senior software designer at AOL. "It doesn't stop when I get home from church or when I go to work."

Sabia first came to know the Lord, as he puts it, six years ago when a Christian colleague at his former job asked if he thought there was a God. Now he spends his lunch hour every Tuesday in prayer and fellowship with a dozen or so other men.

Sometimes, he said, it's hard to contain his enthusiasm for his faith.

"It's one of the things you struggle with," Sabia said. "As evangelical Christians, we are called to go out there, but I don't go around from cube to cube with my Bible saying, 'Repent and be healed.'"

Whether others share his restraint is what most concerns critics of the trend. A tenet of evangelical Christianity is to save the unsaved — to be a "fisher of men." There has long been tension in churches about what that means exactly, with some adopting a much more aggressive approach than others.