THIS TIME President Bush has proposed a "faith-based initiative" that makes even his allies uncomfortable. The target is the Department of Housing and Urban Development, which on the surface seems like Mr. Bush's ideal example of an agency that discriminates against religious service providers. HUD is the only agency whose rules say explicitly that religious groups may not apply for grants. And these are exactly the kinds of grants a typical urban church might need for low-income housing, homeless shelters, counseling services. "Even the playing field" is what administration officials say over and over.

But the president has gone about this particular overhaul rather crudely. Under the proposal, a church would be able to apply for funds to, say, build an addition to be used as a church-run homeless shelter. If the addition were used for that purpose only 30 percent of the time, the government would pay 30 percent of the cost. The rest of the time it could be used for prayer services.

How, exactly, could this arrangement work? Anyone who has been to a church or synagogue or mosque knows that in a place where the spirit moves, activities aren't slotted that way. Should a pastor police a conversation about Matthew that takes place after hours? Or a rabbi rein in a hora that strays into the federally funded kitchen? Should a federal inspector stand by the building with a time clock? Never mind that a series of Supreme Court decisions about religious universities defines precisely how government money can be used for religious structures: The funds can be used only if the whole building is permanently designated for teaching secular subjects.

Joe Laconte at the Heritage Foundation is a staunch supporter of faith-based initiatives, but he says this one makes him uneasy. He and others have proposed a better alternative, which the Bush administration has to date ignored. Mr. Bush, they suggest, should lean more on vouchers; a homeless person could get a voucher at a government shelter and redeem it at a church-run one, which minimizes the entanglement. This arrangement has worked well with child care. For 10 years the government has been easing the way for religious groups to provide child care, and no one's complained or even noticed. The rules are delicately crafted. Money can be used to meet safety standards but not to spruce up the day-care center or to build new structures. The center must be a clearly defined space, and it must be open to inspection. Much of it is done with vouchers. The practice reflects the reality that religious groups are often out there providing crucial services in places where no one else will, and the government should help them where it's appropriate. It can be done, but with care.