Yet another election season is upon us, and yet again the evangelicals are called to action.

For most of his two decades as a preacher, Iowa pastor Mike Demastus eschewed partisanship, telling colleagues and congregants that “religion and politics don’t mix.”

But there he was last month in Ames, making his way across the festive grounds of the Republican presidential straw poll, mingling with political operatives and candidates as he spoke openly about his preference for Rep. Michele Bachmann of Minnesota.

He wasn’t alone. The straw poll drew a slew of previously apolitical Iowa pastors — a constituency increasingly heeding a call to speak out on politics.

“There is a concerted assault on everything that we consider sacred — and we pastors need to move to the forefront of the battle,” said Demastus, wearing a T-shirt and shorts for the Saturday event.

Demastus is part of a growing movement of evangelical pastors who are jumping into the electoral fray as never before, preaching political engagement from the pulpit as they mobilize for the 2012 election.

This new activism has substantial muscle behind it: a cadre of experienced Christian organizers and some of the conservative movement’s most generous donors, who are setting up technologically sophisticated operations to reach pastors and their congregations in battleground states.

Except that this activism isn’t new. It’s been around in some form or another throughout the history of American politics; everything from the Abolitionists through the Prohibitionists to Jerry Falwell and his ironically-named Moral Majority. While there’s no doubt that people with religious convictions have as much a right to participate in it as anyone, the churches have been dabbling in it as much as their congregations — and the tax code — will allow them for as long as there have been election campaigns in America.

The message has always been the same, too. America is on the brink of Armageddon, be it because of demon rum or marrying gays, and the Jesus-shouters are sure that they are the only ones who can prevent it. Of course, they’re going to need money to fight the last battle, and evangelical congregations are always the plumpest pigeons waiting to be plucked.

They’ve formed a bond with the Tea Party — oh, you really didn’t believe they just cared about taxes, did you? As Digby notes, it’s just another re-branding of the same old reactionaries. But now they have ramped it up thanks to unlimited funding from right-wing rich folks like the Koch brothers, who know cannon fodder in the culture wars when they see it.