IN MONTGOMERY County, a politically combustible, potentially ugly debate is brewing that would pit communities of faith against farmers and environmentalists. The battleground is Montgomery's bucolic agricultural reserve, a sweeping tableau of meadows, farms and rustic scenery, constituting a third of the county's acreage, that was shielded 25 years ago from most, but not all, development. The main exception was private institutions such as churches -- and that's the rub. Some residents of the area, as well as environmentalists and public officials, are now concerned that the reserve's character is imperiled by a number of sizable churches -- "megachurches," in their view -- that are seeking to purchase land in the agricultural reserve or have already done so. Priced out of heavily developed neighborhoods down county, the churches intend to build sanctuaries, parking lots and other facilities amid the reserve's turf farms, cornfields and horse pastures. They should be allowed to build -- within limits.

The clash confronts Montgomery officials with a classic balancing act between competing interests over issues freighted with the potential to arouse extraordinary passions. An environmental treasure in a region increasingly marked by tract housing and sprawl, the reserve, located in Montgomery's far north and west, represents the biggest chunk of unspoiled land in the metropolitan area. It was established explicitly to preserve agricultural land, and it has succeeded handsomely: Hundreds of farms and horticultural businesses share space there with horses, cattle, sheep and rolling hills. A number of churches are also located in the reserve, but most are modest structures and some predate the creation of the reserve, in 1980.

What is roiling the waters now is the scale and scope of the churches that propose to expand or relocate in the reserve. Those churches include Bethel World Outreach Ministries, a predominantly African and African American church now based more than 20 miles away in Silver Spring, and Derwood Bible Church, an evangelical denomination currently located near Rockville. Both have large and growing congregations; both have ambitious building plans on substantial properties purchased in the past couple of years. And while both are legally entitled to build on their land, each needs permits and approvals from the county -- and, in Bethel's case, water and sewer service as well -- for the plans they have devised.

Opponents of the churches are not simply or uniformly against the churches' plans; they believe the churches may open the floodgates for other sorts of development in the reserve as affordable land elsewhere in the county soars in price and dwindles in quantity. The churches, on the other hand, have turned to the reserve not mainly because it is green and lovely but because the land there is available and affordable. If they are barred from building in the reserve, church officials say, then they will be barred from building at all.

The Montgomery County Council, which will take up the issue next month, needs to move quickly and deftly if it is to defuse this politically explosive issue. Already, some church officials have leveled loaded accusations that those who would stanch the natural growth of churches are anti-religion. Some environmentalists are depicting the churches' building plans as a mortal threat not just to the county's greenery but to its historical legacy. Soothing words from elected officials will be necessary but not enough: They will also have to fashion a workable compromise that lets stand the churches' property rights while cushioning the impact of building on the reserve. Leaders may wish to consider, for example, a compromise that limits construction on the churches' property to a given percentage of the land, while encouraging the remaining acreage to be devoted to agriculture -- which, after all, is the reserve's purpose. Striking such a deal or another mutually acceptable arrangement will be a test of the council's political acumen. Failure should be unacceptable. It carries the risk of shredding the social fabric of a an increasingly diverse county that is confronting new and, at times, difficult challenges.