The coalition estimates that stringent enforcement of 501(c)(3) could generate up to $16.75 billion in additional annual revenue - almost enough to fund NASA for a year. Less conservative estimates, including an academic paper that pondered the fiscal implications of taxing all churches like for-profit corporations, put that number at $71 billion - enough to send a Mars Rover into space almost every two weeks.

Though the federal government is funded until January 15, the coalition is already lobbying Congress to make it easier for the IRS to investigate and punish rule-breakers as a way of increasing tax receipts. Currently, the IRS is effectively prevented from doing so both because it would start a political firestorm and because of the Church Audit Procedures Act of 1984, which maintains that investigations can take place only with the blessing of a "high-level Treasury official."

"We're trying to use the current budget crisis as an example, as a way to show lawmakers what can be done," says Lauren Anderson Youngblood, Secular Coalition for America spokeswoman. "We're not doing this to hurt anyone. We're not doing this to attack churches or attack religion. We simply want things to be fair."