I came across a group on Facebook today that is working to get the LDS Church stripped of its tax exempt status because of its support of Prop 8. The rumor is that over 50% of the money supporting Prop 8 came from the Mormons and letters were read in all of the churches in California encouraging members to work, volunteer, and give in support of the proposition.
I'm not fond of the idea that the Mormons may have pushed that terrible law onto the books in CA but I'm even less happy about the possibility of outside groups dictating the message or practice of any religious organization.
There are a number of arguments that should be addressed. Some say that tax exempt status is a privilege, gift, or benefit given to churches because they provide some benefit to the broader community and it comes with strings, including not being involved in politics in a substantial way. While that argument may fly for other 501 c3's, it doesn't fly for religious organizations. Religious groups are not taxed because the government has no say over them. The power to tax is the power to control and the state has no power when it comes to religion.
Others frame the tax exempt status as a subsidy to religious groups. While it is true that many religious organizations could not survive, at least in their current forms, if they had to pay taxes, again, this implies some gift that the government has the power to give or withhold from religious groups. It has no such power to give or to withhold.
A serious fallacy that is common in the US is the idea that religion is not supposed to be political. How can it not be if it is worth anything at all? If faith impacts an individual's values, is that not political? Doesn't that inform who we vote for and what ideas we support? If it impacts how they live their daily lives, is that not political? If religion speaks to what is important in life, is that not political? When we look at Jesus, the central metaphor for his ministry was a political one - the Kingdom of God. The history of social movements in the US is a history of religious groups acting politically whether it be the idea of religious freedom which found its strongest proponents in the Baptists and the Quakers, the elimination of slavery, women's rights, worker's rights, the civil rights movement, the anti-war movement... none of those political movements would have existed without people of faith acting politically from a standpoint of their religion.
Now one might argue that it is OK for people of faith to act poltically as individuals but not as groups. That betrays a misunderstanding of the diversity of faith groups. That certainly fits in the free church tradition, in many threads in Judaism, and in a number of other faith traditions which emphasize the role of the individual in shaping their own faith. In other groups, such as Catholicism and the LDS on a global level and even some fundamentalist churches on a more local level, the shape of faith is dictated by a hierarchy that literally defines what is and is not orthodox and who is in or out of the flock. In those settings, a political directive makes sense. A bishop might reasonably tell all of the members of his diocese that to vote for a certain pro-choice candidate is to risk excommunication. Likewise an LDS leader might tell all of the faithful that support for prop 8 is required to be a Mormon in good standing (I don't know how the encouragement was framed so this is just an example). Or a fundamentalist pastor may tell his congregation that they must believe a certain way which must be reflected in a vote for or against a certain candidate. Such prescriptions are built into the religion.
As a pastor, I think it is stupid to try to tell people how they should vote or what political stances they should take. In this age of baptistification (google the term, used by Martin Marty in the 80's), I think even the connectional churches risk serious problems when they try to dictate the beliefs of their constituents. Still, it solidly fits in their traditions and for the government or the people to try to curtail that practice seems clearly to be in violation of the 1st Amendment in that it impedes the free exercise of that religion.