Last July, when the Fairfax County Board of Supervisors refused to allow the Fairfax Christian School to build a new facility on land zoned for single-family homes, the school's founder called it "an attack on Christianity."

Only a few months before, Fairfax's zoning administrator had led the county into a hornet's nest when he proposed that its zoning code be rewritten to spell out what churches may and may not do with their property. In that case, the supervisors beat a hasty retreat after church groups protested that the county had no right to regulate their activities.

In Fairhaven, Mass., local zoning officials brought down a similar storm this spring when they ruled that Bible studies were home occupations and therefore prohibited under the town's property-use ordinances.

And in Los Angeles, officials ruled that home-occupancy regulations forbade Orthodox Jews from holding prayer meetings in their homes.

All across the country, separation of church and state -- an issue often addressed but never resolved in the United States -- continues to provoke heated debate. But now the old dispute has found a new and perhaps unexpected forum: the nation's local zoning and planning boards.

From mainstream denominations to fast-growing fundamentalist churches, parishioners are questioning the authority of local zoning bodies to regulate their activities.

These challenges strike at powers local agencies have long taken for granted, such as their ability to impose limits on at-home Bible study or church schools; to require review of architectural changes or plans to demolish older churches, in keeping with historic preservation rules; and to withhold permits for new churches and church schools for reasons ranging from traffic congestion to inadequate sewer capacity.

"We have problems with zoning restrictions because we believe in our right to exercise our faith, and you need property to exercise your faith," said Robert Thoburn, headmaster of the private Fairfax Christian School. "It goes back to the basic freedom everyone has, to use their property for what they want. Where else are you going to meet for worship or to teach your kids?"

The debate is intensified because it comes at a time when homeowners, particularly in growing areas, are struggling to maintain the residential character of their neighborhoods in the face of pressure for higher-density housing and commercial development.

These homeowners, in turn, are putting pressure on local officials to take a hard line against any land use that the community considers intrusive.

In areas of the country experiencing rapid growth or redevelopment -- and thus rapid growth in the number of churches -- some local governments have felt pressed to increase the restrictions on churches and church-use in efforts to keep religious organizations from adversely affecting surrounding neighborhoods.

Churches traditionally have been considered good neighbors, but today the placid picture of a church steeple rising above the trees and roofs of a quiet neighborhood sometimes belies the truth of what residents see and experience during peak periods for church activities.

Fast-growing churches with large, involved congregations can quickly exhaust neighborhood parking space and may push aggressively to expand buildings and grounds, sometimes seeking to build schools and day-care centers.

In one Fairfax County neighborhood, for example, a church built a bus repair facility next door to maintain its fleet of buses. Other churches in residential areas are providing shelter for the homeless or opening soup kitchens, attracting people who some homeowners say they do not want in their neighborhoods.

Such a fight flared up this past spring in Fairfax County, opening what one supervisor called "a can of worms we're going to wish we had never opened."

It was in an attempt to settle the question of shelter for the homeless that the county zoning administrator suggested writing permitted church uses into the zoning code. Before this, churches had to get special-exception permits from the county on a case-by-case basis to do any building.

Reaction was quick and hostile.

"Where is the separation of church and state when we look at an ordinance such as this?" asked Dennis Patrick of the Christian Assembly of Vienna at a public hearing on the proposal.

"An effort is being made to move against private ownership of property," said Neil Markva, head of the Rutherford Institute, a conservative group that defends religious liberties. "Possession and the right to use the land are being infringed on."

Several Fairfax citizens groups supported the proposal, however, saying that homeowners "had a right to be protected by the governing body of the county, not the governing body of any particular church."

The supervisors rejected the zoning administrator's plan several weeks later, deciding to keep the special-exception process, but not before doing what several supervisors called "significant damage to the formerly good working relationship between the county and county churches."

"We had been getting along just fine with the special-exception permit process for churches," said Supervisor Audrey Moore. "It was not one of our finest hours."

The churches involved in that case, which have operated an emergency shelter for the homeless in the Rte. 1 area for the past two winters, have been under pressure from some neighborhood organizations to stop housing the homeless in their sanctuaries, most of which are located in middle-class neighborhoods.

Fairfax officials, seeking to defuse the situation, promised the churches earlier this year to open a county shelter. Last month, however, county officials said that, because of protests from other neighborhood groups, they may have trouble finding a location for the shelter. They added that they will not build a shelter in an area where citizens don't want it.

Other communities across the United States have experienced similar confrontations after trying to impose secular rules on religious institutions.

The D.C. Department of Finance and Revenue, for example, collided with church groups last winter over regulations aimed at defining church uses -- in this case a proposal to set new standards for nonprofit organizations seeking tax-exempt status. Under that proposal, churches could not qualify unless they used 60 percent of their floor space for religious services for 30 percent of the time they were open. Many of the city's churches, which use their buildings for a variety of activities including youth-group and club meetings, said they could not meet that test.

The department dropped the proposal after churches citywide protested the definition as an unconstitutional attack on religious freedoms guaranteed in the First Amendment.

"It used to be recognized that churches provided a unique service to the community, and, unless there were extenuating circumstances, they should be allowed to carry on their activities," said Kevin Ikenberry, associate staff counsel for the Rutherford Institute. "Now there is more of an attitude that they shouldn't be allowed any special treatment under the zoning laws."

The fact that churches have expanded their functions to include day care and schools, say zoning attorneys, has complicated the situation. It used to be that single-family neighborhoods accepted churches, parks and schools as part of their communities. But that is changing, in part because some churches are violating zoning restrictions and pushing special permits beyond what localities have allowed.

"It used to be you could put a church almost anywhere, but churches have expanded their functions, and the rules the county has have expanded also," said Edward Pritchard, a zoning attorney in Northern Virginia. "The board of zoning appeals is getting very tough" on what it allows.

Church Growth Services International, a consulting firm in South Bend, Ind., that advises churches on how to organize and finance building programs, now includes zoning lawyers on teams that go out to cork with clients.

Church Growth President William Walters said that many churches today are opting to erect multipurpose sanctuary buildings that also can be used for church schools and day-care centers, bringing week-long activity to places formerly active only on Sundays.

In Ohio, a battle over whether the state should require church-run day-care centers to meet state licensing standards brought together a number of churches defending their right to exercise their religion without government interference.

"The Lord says that some things belong to Caesar. . . . However, we are to see that some things do not belong to Caesar, for God has reserved certain areas unto Himself," said Alan N. Grover, a Ohio minister who organized the fight against the state licensure bill. "Thus we are to understand the principle of limited government, for the civil authority may not arrogate to itself powers which are reserved by God."

Among Washington-area jurisdictions, the problem has been most acute in fast-growing Fairfax. The county recently has faced a string of zoning battles over proposals by churches -- most of them fast-growing fundamentalist congregations -- sparking widespread public debate over the role the county should take in restricting church land use and location of new churches.

Christian Fellowship Church, a large church on Rte. 7 near Reston that has grown substantially since it was founded in 1977, recently was refused a request to expand its church and build a school. The Fairfax County Board of Zoning Appeals, which must review all church requests for land-use permits, said it did not believe the neighborhood could support the increase in traffic the school would bring.

Christian Fellowship sued the board, claiming that the ruling "failed to grant the church its constitutional right to equal protection of the law and its constitutionally protected right to the free exercise of religion.

"To prohibit the church from expanding its physical plant to meet the needs of its congregation . . . is to unconstitutionally abridge the church's free exercise of religion," the church argued.

Fairfax County Circuit Court Judge J. Howe Brown, however, upheld the board, saying that "a church, like any other institution, is subject to zoning laws."

Brown said the board was "fully justified in disbelieving" the applicant's contention that the "expanded facility would not have any adverse impact on traffic."

Lawyers specializing in First Amendment freedoms, including freedom of religion, say that, in general, courts have been unsympathetic to churches' claims that local zoning laws are an unfair intrusion into their religious activities.

"So long as the zoning law is not directed specifically at the religious activity, but instead affects it as a secondary issue, most courts have ruled the zoning law is constitutional," said Geoffrey Stone, a professor at the University of Chicago Law School. "The courts have been extremely skeptical of religious organizations claiming special dispensation."

Some religious leaders, however, believe that localities should not regulate churches beyond the basic health and safety issues, saying that the few individual cases of abuse do not justify the broader restrictions.

"I think you are better off tolerating a certain amount of abuse from the problem cases and having a free society than throwing the churches out of a community because of those few cases," said John Thoburn, who calls himself a "Christian activist." "If a church gets too much bad publicity, it hurts them. Few churches are really going to be a problem."

Robert Thoburn, John Thoburn's father and a former Virginia state legislator who has helped organize Christian schools throughout the United States, said he believes the rights of churches to use their land and buildings as they need is more a question of basic property rights than of religious rights.

"We need to begin with the fact that God owns the land. We are stewards of the land. We are to use it to his glory," Thoburn said in a recent book on Christian activism. "Land-use laws are being used to restrict citizens in various ways. They are being used to prevent churches from building and to curtail the Christian school movement."

When the Fairfax County Board of Supervisors turned down Thoburn's request to be allowed to build a school on land zoned for one-acre single-family lots, Thoburn said that if he couldn't win at the county level, he would try to bring the issue to "the court of public opinion." His plan: a new state law that would grant churches and private schools exemptions from local zoning laws.

"I'd rather be at the mercy of churches having total freedom than at the mercy of government restricting churches," Thoburn said. "I think people will get progressively angrier about it."