Russell Kirk often used to make the point that conservatism (properly so called, as George F. Will would say) is not an ideology. This was implicit in his deeming of conservatism as the "politics of prudence." An ideology is a political philosophy operating like a religion: It is apocalyptic, messianic, utopian, and radical.
You know you are a ideologue if, solely on the basis of your political views, you can fill in the blank of the following question: "The world will be brought to perfection when ____________."
Modern left-wing liberalism has always been ideological in this sense. They can complete the statement above. For them, the world will be perfect when the society no longer interferes with our advance toward self-fulfillment. There can be a utopia if we take radical action to bring it about. It will be established in that Last Battle, when the forces of political darkness (conservatives) are defeated by the forces of the political light (left-wing liberals). In the meantime, we must settle for passing government programs.
This is what William F. Buckley (quoting Eric Voegelin) meant when he accused liberals of "immanentizing the eschaton": They want to bring about in the here and now what can only be brought about in the afterlife or in the religious apocalypse that will ensue before a Last Judgment they don't believe in.
Left-wing liberalism being a religious belief masquerading as a political one, it only makes sense that its most central belief would be theological: The denial of Original Sin. Left-wing liberalism is the political analog of the Ghost Dance movement, the cargo cults, and the Shakers, only without the religious trappings. They all sought a heaven here on earth and thought that through their actions they could either prepare for it or help bring it about.
Jean Jacques Rousseau, not Karl Marx, is the left-wing liberal's patron saint. Rousseau's "natural man," uncorrupted by civilization contrasts with the conservative idea that civilization is the only thing keeping man from destroying himself and everybody else.
Left wing liberalism's view that utopia is possible and that man is perfectible--and that all this can be accomplished through the right policies--is an idea that is increasingly characteristic of modern conservatism. And this is why we had the knee-jerk reaction of so many so-called conservatives to Pope Francis' comments that the free market was not sufficient to accomplish what needed to be accomplished with the poor.
The idea of the free market now serves the same role for many conservatives as government action serves for many liberals: It has become the policy by which we can reach an earthly Nirvana. Conservatives now seem to see the right set of policies as the route by which we can reach terrestrial perfection. The way to do this, they say, is a completely free market.
Traditional conservatives do not view the free market in this way. It does not view it as a cultural panacea. Free market capitalism is indeed the most efficient economic system, but that doesn't mean that it's perfect. It is the worst economic policy ever developed by mankind, to borrow an expression from Winston Churchill about systems of government, except all the other economic policies that have been developed from time to time throughout history.
All the Pope was trying to say was that the free market was not a panacea and it didn't release us from the obligation to help the poor. Many conservatives interpreted this as the Pope attacking the free market per se. But an attack on the idea that the free market is not a panacea is not an attack on the free market. It is an attack on a mistaken belief about the free market.
It is a plea from a religious leader not to make politics (or economics) into a religion.
This is why many conservatives do what traditional conservatives would never have done: called their political position an ideology--a "conservative ideology." They too place celestial faith in earthly things. Conservatism is not an ideology and when it becomes one, then it isn't conservatism any more.