Religious tax-exempt status and campaigning: church-and-state or religion-and-politics?

We in the United States have a political doctrine of "separation of church and state." As commonly interpreted, the First Amendment says that government should not interfere with private citizens' "free exercise" of religion and should not "establish" an official state church. But this separation is often misinterpreted to mean that religion and politics should never mix, even though this view is contrary to what has always been the case in the U.S. For example, a person's religious beliefs and affiliations can inform and influence his or her politics, and religious groups are free to speak out on political issues with moral dimensions. Nothing is illegal about either of these infusions of religion into politics. Nonetheless, the boundaries between disallowed church-state relations and allowed religion-politics interplay is continually negotiated, and the rules of the game can change.

One of the boundaries being challenged is that which prohibits religious groups from supporting political candidates. As legally recognized institutions, religious groups are subject to tax laws, and most are registered as non-profit institutions--classified 501(c)(3) so you can write off your donation to your church from your taxes. If a religious group campaigns on behalf of a candidate, then its tax-exempt status is jeopardized. Losing tax exempt status is a BIG deal, so a religious group would not want to lose it. The economic logic behind wanting tax-exempt status is straightforward. Tax-exempt status decreases costs (churches do not have to pay taxes on their income), and because in the U.S. the government does not financially subsidize religious groups' primary activities, tax-exempt status allows for larger financial donations (the cost of contributing is lower to taxpayers because it is a tax write off). In short, tax-exempt status greatly improves a religious group's ability to provide religious goods and services in the American religious market. For more details on what is prohibited and why see this excellent Guide to the IRS Regulations compiled together by the Pew Forum on Religion and Public Life.

As described in this Pew Forum article, religious leaders are challenging the law that prohibits their involvement in campaigns. Yet, as the article states:

"While a strong majority of Americans support religion’s role in public life, a solid majority also expresses opposition to churches coming out in favor of particular political candidates."

What economic logic is behind the argument against the current rule? What economic logic is behind the argument for the status quo?