To do otherwise would be an intolerable government intrusion into employment relationships that courts have called “the lifeblood” of religious life and the bedrock of religious liberty, explained Edward R. McNicholas, co-chairman of the national religious institutions practice in the Washington, D.C., office of Sidley Austin, a law firm with some of the country’s largest religious organizations among its clients.

Judges have routinely invoked the ministerial exception to dismiss lawsuits against religious employers by rabbis, ministers, cantors, nuns and priests — those “whose ministry is a core expression of religious belief for that congregation,” as Mr. McNicholas put it.

But judges also have applied the exception to dismiss cases filed by the press secretary at a Roman Catholic church, a writer for The Christian Science Monitor, administrators at religious colleges, the disgruntled beneficiaries of a Lutheran pension fund, the overseer of the kosher kitchen at a Jewish nursing home and a co-founder of Focus on the Family, run by the conservative religious leader James C. Dobson. Court files show that some of these people were surprised to learn that their work had been considered a “core expression of religious belief” by their employer.

Religious employers have long been shielded from all complaints of religious discrimination by an exemption that was built into the Civil Rights Act of 1964 and expanded in 1972. That historic exemption allows them to give preference in hiring to candidates who share their faith. In recent years, some judges have also refused to interfere when religious groups have dismissed lesbians, unwed mothers and adulterous couples, even if they profess the same faith, because they have violated their employers’ religious codes.

A federal court decision has given religious broadcasters an exemption from some of the fair-hiring requirements of the Federal Communications Commission, even when they are hiring secretaries and receptionists. Two other decisions, one in federal court affecting a Mormon church and the other in a state court of appeals case involving a Roman Catholic nursing home, affirmed the right of religious employers to dismiss employees whose faith changed after they were hired.

“These are very difficult cases because they pull at some very fundamental heartstrings,” said Steven C. Sheinberg, a lawyer at Outten & Golden, specializing in employment law. “There’s our belief that employees should be free of discrimination in their work, versus our belief that religious organizations should be free to hire people who best help them fulfill their religious mission, without the intrusion of government.”

Employees at religious institutions face other risks as well, thanks to pension law exemptions granted by Congress and upheld by the courts. Religious employers are exempt from Erisa, the federal pension law that establishes disclosure requirements and conflict-of-interest restrictions for employee pension plans. That exemption has given rise to several cases in which workers at religious hospitals found that their pensions had vanished because of practices that would not have been allowed under Erisa’s rules.