Pope Francis is causing quite the stir these days.

On Tuesday he will make his first trip to the United States, where he'll preach the existential urgency of climate change and the moral imperative of economic inequality to a Republican Congress that would probably prefer he talk about abortion and marriage. Conservatives worldwide are upset that Francis is allowing priests to absolve women who repent for an abortion and has "vandalized" marriage by making it easier for Catholics to get their marriages annulled.

In July, Gallup reported that the pope's favorability among American self-described conservative Catholics had dropped to 45 percent, from 72 percent a year earlier. "This decline may be attributable to the pope's denouncing of 'the idolatry of money' and linking climate change partially to human activity, along with his passionate focus on income inequality," Gallup said, noting that these are "all issues that are at odds with many conservatives' beliefs."

But just because some conservatives are upset with Pope Francis, that doesn't mean that he's a liberal. He isn't, really, politically or religiously.

He is a reformer, and he is shaking things up in a church that had experienced theological and institutional continuity for 35 years under Pope John Paul II, elected in 1978, and Pope Benedict XVI, John Paul's doctrinal right hand from 1982 until his own elevation to supreme pontiff in 2005.

Francis boldly promotes some policies that make conservatives uncomfortable. But the Pope Francis revolution is probably best described as humanist — and that makes it a much bigger challenge to Catholics in the West, both conservative and liberal.

Let me be clear: I'm not arguing that Francis is a secular humanist, or capital-h Humanist, by any means. Instead, let's call him a Christian humanist, defining that as one who cares about human beings more than ecclesiastical considerations.

That might sound like secular balderdash, but it's actually a phrase coined by Pope Benedict. "Christian humanism," he wrote in the 2009 encyclical Caritas in Veritate ("Charity in Truth"), "enkindles charity and takes its lead from truth, accepting both as a lasting gift from God. Openness to God makes us open toward our brothers and sisters and toward an understanding of life as a joyful task to be accomplished in a spirit of solidarity." Benedict explicitly borrowed the idea from Pope Paul VI.

Pope Francis has taken the idea of Christian humanism and put it into practice, with a big smile. He is concerned with the welfare of the Roman Catholic Church, certainly, but he is much more concerned with what the Catholic Church calls the "mystical body of Christ" — that is, the people who make up the Christian church.

There are plenty of examples.

His groundbreaking encyclical on climate change, Laudato Sí ("Praise Be to You"), for one, is a stern rebuke to humanity — that includes industrialist polluters, but also voracious consumers and even environmentalists — for turning the Earth into "an immense pile of filth." But he intrinsically pairs ecology and social justice, arguing that efforts to save the planet "must integrate questions of justice in debates on the environment, so as to hear both the cry of the Earth and the cry of the poor."

Then there's the pope's modification of church law to make it easier to get broken marriages annulled, which, Vatican Radio says, is rooted in the core principle of "salus animarum — the salvation of souls." Catholics whose marriages fail — especially in poorer countries, where annulments are expensive and hard to come by — should be shown mercy and love, encouraged and allowed to fully participate in the sacramental life of the church, whenever possible.

But probably the most illuminating example — the one that shows Francis putting the needs of humanity firmly above the parochial concerns of the church — has to do with the Christian character of Europe.

Pope Benedict, before he retired, fought tooth and nail to keep Europe anchored in Christianity. In 2007, after the European Parliament rejected including references to God and Christianity in the European Constitution, Benedict chastised European lawmakers. How can EU governments "exclude an element as essential to the identity of Europe as Christianity, in which the vast majority of its people continue to identify?" Benedict asked. "Does not this unique form of apostasy of itself, even before God, lead [Europe] to doubt its very identity?"

Pope Francis has not only ignored the issue, he has pleaded with Catholics — and, in fact, all Europeans — to personally house the masses of mostly Muslim migrants seeking refuge in the EU.

The surge of humanity from Syria, Afghanistan, Iraq, and Libya will make Europe more Muslim and less Christian, as some European politicians have noted caustically. But the preeminent Christian leader in Europe is begging Europeans to open their doors, anyway. And in the case of Catholic religious orders, he is more than pleading: He is ordering them to utilize their unused convent and monastery rooms to house refugees, unless they want to start paying property taxes. The Holy See has already chosen two families of migrants to stay in the Vatican, the pope said, and they are welcome to remain "as long as the Lord wants."

If you think that the church focusing on migrants isn't novel, you wouldn't be wrong. Pope Benedict said it was "impossible to remain silent" on the issue of refugee camps in 2008 (years before the refugee camps were in Europe). And, back in 1985, John Paul II said the fact that a migrant "is a citizen of a particular state does not deprive him of membership to the human family." In the U.S., the Catholic Church has long advocated for the rights of immigrants — though the big waves of immigrants in the 20th century were largely Catholic.

But that's the point of the Pope Francis revolution — it's not really about new ideas, it's about what the Catholic Church truly focuses on and where it leads by example. Francis isn't just visiting the sinners in the U.S. Congress, he's also visiting the sinners in prison, as well as children, hard laborers, refugees, and other demographics the Bible says that Jesus paid attention to.

Ostentatiously living a more humble papacy, determinedly mingling with the disenfranchised and downtrodden, radically (for the Catholic Church) putting the laity at the center of church solicitude: This is the change Francis is bringing to the Catholic Church. It is making lots of people uncomfortable. Honestly, any Catholic that doesn't feel challenged by Francis' subversive papacy probably isn't paying enough attention.

Cardinal Timothy Dolan, the archbishop of New York, calls Francis "an equal opportunity disturber," noting that "when we listen to some things he says, we smile; as we listen to other things he says, we bristle." But, he added, "Jesus was like that, remember?"

It's pretty clear Pope Francis does.