This week, dozens of U.S. pastors mailed copies of recent politically charged sermons to the Internal Revenue Service complaint office in Dallas.

They're daring the IRS to challenge their churches' tax-exempt status in hopes of a legal battle that could overturn the 1954 Johnson Amendment prohibiting them from engaging in political campaign activity.

It's time for the IRS to take up that challenge and stop treating religious leaders who blatantly violate the federal tax code as a protected class. Existing law is clear that houses of worship should not be allowed to become houses of partisan politics while maintaining tax-exempt status.

And no politician, liberal or conservative, should be able to use a church as a tax shield.

If there were a Christian Tea Party movement, these pastors would be on the front lines. They see IRS laws designed to protect taxpayers as an unnecessary government intrusion that tramples the freedom of religion guaranteed in the U.S. Constitution.

They believe that freedom means being able to say whatever they want on the job without jeopardizing a valuable tax-exempt status.

This isn't about politics but about religious freedom, says Eric Stanley, an attorney with the Alliance Defense Fund (ADF), a conservative Christian organization that sponsors Pulpit Freedom Sunday -- a day when religious leaders intentionally deliver political sermons.

Not only did some pastors endorse or condemn candidates at the annual event on Sept. 28, they made sure the IRS knew about it.

The ADF wants to challenge the constitutionality of the tax provision, which was authored by then-U.S. Sen. Lyndon Johnson. Congress amended the law in 1987 to make it clear that the prohibition against campaigning for candidates also applied to acting in opposition to candidates.

But the matter has gotten out of hand and has grown into a public showdown because the IRS hasn't enforced the tax-exemption rules effectively.

In 2006 -- the latest data available -- the IRS investigated 100 churches, found that 26 violated the rules and, as a result, issued written citations.

In other words, the chances of a church having its tax-exempt status revoked under the current system appear slim.

Last century, polls frequently showed that the majority of Americans supported the marriage of politics and religion in houses of worship. But recent surveys reveal those views are sharply changing, even among religious conservatives.

Since 2004, two-thirds of Americans have said houses of worship should not endorse or denounce candidates, according to the Pew Research Center.

That means the majority of Americans don't want to hear political advocacy from pastors such as Gus Booth of Warroad, Minn., who in 2008 told his congregation, "If you are a Christian, you cannot support Hillary Clinton or Barack Obama," before launching into a scathing critique of the candidates.

Booth was reported to the IRS by Americans United for Separation of Church and State, a watchdog organization that says the tax rules, in fact, help safeguard religious freedom.

"Booth is free to endorse anyone he wants as a private citizen," the Rev. Barry Lynn, head of Americans United, said at the time. "But when he is standing in his tax-exempt pulpit as the top official of a tax-exempt religious organization, he must lay partisanship aside."

GOP presidential candidate Michele Bachmann of Minnesota said last year that she'd like to see the federal tax restriction scrapped. A Brooklyn Park pastor, Mac Hammond, recently said he'll support her candidacy, though not from the pulpit, as he did in 2006.

After that pulpit endorsement, the IRS sought to audit the financial records of Hammond's Living Word Christian Center. But the church got off on a technicality; a judge ruled that the IRS official wanting the information wasn't of a sufficient rank.

Since then, the IRS has backed off from pursuing cases aggressively, which is the wrong approach.

Federal law requires a "high ranking" IRS official to launch any investigation. The law needs to be clarified as to what this means, and the IRS should act now to make sure such officials are in place so that religious leaders and organizations cannot skirt the law.

* * *

Readers, what do you think? To offer an opinion considered for publication as a letter to the editor, please fill out this form. Follow us on Twitter @StribOpinion and Facebook at facebook.com/StribOpinion.