Groups purporting to be religious and, therefore, exempt from taxation should beware they don’t endanger that exemption with their political activities.

For example:

James Dobson’s Focus on the Family, a group that has nonprofit status and allows contributors to deduct contributions from federal taxes, has raised $336,000 of the $2.3 million that groups opposed to same-sex marriage have donated to support Proposition 8, the Nov. 4 ballot initiative banning same-sex marriage, according to the Los Angeles Times.

The president of the Church of Latter Day Saints (LDS) issued a letter last Sunday “from the pulpit” urging members to donate “means and time” to pass Proposition 8.

Pastor Jim Garlow of the 2,500-member Skyline Church in San Diego, recently convened a conference call in which “more than 1,000 ministers, most from evangelical congregations, discussed tactics for passing [Proposition 8].”

It’s no stretch to say that such religious leaders are transforming their churches into campaign headquarters, geared to pass Proposition 8 (and Proposition 4, which prohibits abortion for unemancipated minors until 48 hours after her physician notifies her parent, legal guardian or adult family member). Expect to see the flock manning phone banks, distributing door hangers, and conducting “precinct” walks in an effort to influence elections so that public policy embodies their religious beliefs.

None of us would have any problem with this, if it weren’t for the fact that these religious groups receive tax-exempt status. They don’t pay taxes on their vast incomes; they don’t pay property taxes on their billions in holdings. And contributors receive a tax deduction.

Many of us contribute funds to political groups that may be nonprofit, but they are not tax exempt because they are political. Unless we receive the same tax-exempt status, it’s not a fair playing field. And it’s reached a point where Attorney General Jerry Brown has more than probable cause to investigate whether such “religious” groups are defrauding the state by presenting a façade of worship when they are actually masquerading as political campaign headquarters.

Historically, under federal and state law, we view religious groups as deserving of tax-exempt status because they are not political and provide charity to so many. But when they cross the line and become political, they jeopardize the public subsidy they enjoy.