It looks like 2015 is shaping up to be the year when Catholic conservatives declare war on Pope Francis.

We heard the first rumblings last fall, when the preliminary draft of a statement produced by the extraordinary Synod on the Family inspired New York Times columnist Ross Douthat to warn ominously about the possibility of a schism in the church if the Vatican loosens doctrinal strictures against divorced (and remarried) lay people receiving the sacrament of Communion.

But most Catholic conservatives have held their tongues, working to put a positive spin on papal pronouncements that many of them find increasingly alarming. (Sure the pope’s denunciations of capitalism are galling, but listen to his passionate attacks on abortion! Yes, Francis is far too nice to gays, but he gave such an inspiring speech on the last day of the Synod!)

So far, the tactic has worked — at least until now.

Interestingly, the decisive provocation appears to be the pope’s forthcoming encyclical on the environment.

On Jan. 3, Robert P. George assured readers at First Things that they could safely ignore whatever the pope might say about climate change because his arguments would be based on contestable empirical claims about which Francis possesses no special expertise. Two days later, author Maureen Mullarkey wrote a blistering blog post, also at FT, in which she went much further — to condemned the pope as “an ideologue and a meddlesome egoist” who views “man as a parasite” and “sullies his office by using demagogic formulations to bully the populace into reflexive climate action with no more substantive guide than theologized propaganda.” (FT editor R.R. Reno disowned the Mullarkey post later in the week.)

Finally, on the same day that Mullarkey’s post appeared, Catholic columnist Steve Moore denounced Francis in Forbes, calling his public policy pronouncements on economics and the environment a “complete disaster” that show that he’s “allied himself with the far left and has embraced an ideology that would make people poorer and less free.”

Looks like the honeymoon is finally over.

The question is why now — and why over the environment of all things?

The answer, I think, is that the environment, in itself, has very little to do with it. The problem is simply that Francis has broken from too many elements in the Republican Party platform. First there were affirming statements about homosexuality. Then harsh words for capitalism and trickle-down economics. And now climate change. That, it seems, is a bridge too far. Francis has put conservative American Catholics in the position of having to choose between the pope and the GOP. It should surprise no one that they’re siding with the Republicans.

Under Popes John Paul II and Benedict XVI, a number of neoconservative Catholics (or theocons) went out of their way to make the case for the deep compatibility between Catholicism and the GOP. But not just compatibility: more like symbiosis. For Richard John Neuhaus, Michael Novak, George Weigel, and their allies, the GOP would serve as a vehicle for injecting Catholic moral and social ideas into American political culture — while those Catholics ideas, in turn, would galvanize the Republican Party, lending theological gravity and purpose to its agenda and priorities.

In the hands of the theocons, the Republican platform became more than a parochially American mishmash of positions thrown haphazardly together for contingent historical reasons. Rather, it was a unified statement of High Moral Truth rooted in Thomas Aquinas’ medieval theology of natural law — the most highly developed outgrowth of Christian civilization.

Opposition to abortion was bound up with hostility to euthanasia and same-sex marriage as well as with support for domestic policies that encourage traditional family life — with all of these flowing from an overarching commitment to a “culture of life” and resistance to a “culture of death.” This commitment also justified an assertive American foreign policy that championed freedom, imposed global order, and upheld the highest standards of international justice. And of course, the vision of the free society that guided American foreign policy was one with relatively low taxes and minimal government regulations in which the primary burden of charity and other support for the poor falls primarily on individuals and local communities.

To be a devout Catholic and a conservative Republican in the three decades separating Ronald Reagan’s first term and the start of Pope Francis’s pontificate in March 2013 was to feel virtually no tension between one’s political and theological commitments. Which isn’t to say that conflicts never arose. Occasionally they did — when John Paul or Benedict spoke out against the death penalty, pointed out injustices endemic to capitalism, or expressed concerns about the latest American war. But there was always a theoconservative writer at the ready, willing and eager to accentuate continuities with the GOP and explain away the difficulties.

That has become ever more untenable in the 22 months since Francis became pope, as the points of divergence have multiplied. With the release of an encyclical that looks likely to break forcefully with the climate-change denialism that has become a fixture of the Republican mind, American conservatives appear to have reached a moment of decision: Should they side with the party or the pontiff?

Mullarkey and Moore, at least, have made it very clear where they stand: with the GOP and against the pope. Robert George, meanwhile, remains committed to the old theocon strategy of explaining away the difficulties — of telling Catholic Republicans that there’s no need to choose, because GOP ideology and Catholic social teaching go together just as easily and happily as ever.

Except that, increasingly, they don’t — as more and more Catholic Republicans are coming to understand.

The war is underway, and there may well be nothing the theocons can do to stop it.