In homilies, lectures, op-ed articles, books, and a weekly online column, Chaput unflinchingly assails presidents, lawmakers, academics, and the media when, in his opinion, they "marginalize God."
Writing in last Sunday's Inquirer, he described as "dangerous and insulting" the Obama administration's mandate that religious-affiliated hospitals, schools, and charities provide employees with free contraception coverage.
President Obama's plan was the most "aggressive attack on religious freedom in our country . . . in recent memory," Chaput wrote, lambasting it as "the embodiment of a culture war."
Taking their cues from the United States Conference of Catholic Bishops, many other prelates condemned the policy. But Chaput's attack stood out, eliciting praise from conservative Catholic groups and dismay from church liberals.
"Incendiary and divisive," said a spokesman for Catholic Democrats, a liberal advocacy group for the poor.
Branding Chaput a "Taliban Catholic," Sean Michael Winters, a columnist for the liberal weekly National Catholic Reporter, said the tone of the column "invited people not to look at the details" of Obama's proposal.
Conservative Catholics disagreed.
"Brilliant," the National Right to Life News called Chaput's essay.
It was the most-viewed item last week on the Catholic News Agency's website. It also prompted 167 comments on The Inquirer's website, where opinion ran about 2 to 1 against him.
"Get out of the dark ages," one reader chided.
Another cheered, "Our church has sorely needed a voice like [Chaput's] for years."
An unscientific sampling of local Catholics, based on random interviews at 30th Street Station, suggested many do not share their archbishop's position in the contraception debate.
"I'd rather see his energies more focused on issues people can rally around," such as education and the environment, said Lauren Bobzin, 25, of Narberth, who called herself a "proud Catholic."
Bill Quain, 33, of Northwest Philadelphia, said he thought Chaput was "pretty much giving the party line."
And a retired schoolteacher from Narberth who asked not to be named said she disagreed with Chaput's stance on birth control but called him a "breath of fresh air."
Obama compromised on the contraception mandate: Insurance companies, not religious entities, would provide coverage. But the Catholic bishops - Chaput included - quickly denounced the change as no better. Meanwhile, political analysts wondered aloud whether the bishops had enhanced or damaged the president's standing with Catholic voters.
Chaput declined to be interviewed for this article. However, in his weekly column at archphila.org, he took aim at "the contempt dumped on Catholic teaching" in last week's media accounts of the bishops' feud with Obama.
"The Christian life does not need aggression," he wrote. But if Catholics feel their faith or values are under assault, "they need to fight - without apologies - to turn things towards the good."
He also sounded that rallying cry in a Jan. 26 online column in which he exhorted his flock to demand that state lawmakers authorize vouchers for private-school tuitions. "Elected officials do listen," he wrote, "and they act when the noise gets loud enough."
Though a hero to many conservatives, Chaput has taken shots from all sides. "The left mail I get will use terrible words but be less vitriolic. They use the F-word and things like that," he told Catholic News Service in 2009. "The right is meaner, but they're not as foul."
Yet for all his hammer-swinging, he also enjoys a reputation as an eloquent, erudite evangelist.
"Our culture has fallen away from our own biblically informed heritage," he told an audience at the University of Pennsylvania in the fall. "We've lost the foundation for our moral vocabulary. This loss has starved our spirit [and] debased our sense of any higher purpose to life."
In a similar talk in the fall at Assumption College in Worcester, Mass., he cited historians Daniel Boorstin and Alexis de Tocqueville; French philosophers Pascal Bruckner and Jacques Maritain; Jesuit scholar John Courtney Murray; St. Augustine; a fourth-century Roman pagan named Symmachus; and Jesus.
"I'd say he's one of the top three voices among the American bishops," said Deal Hudson, director of Catholic Advocate, a political action committee in Washington.
"I'd put him at number one," said Phil Lawler, editor of the Catholic World News in Boston. Both men are past editors of Crisis, a conservative Catholic magazine.
Liberal pundits also describe Chaput as a commanding presence among bishops.
"Nobody speaks with the same consistency and muscularity as he does," said Steve Krueger, national director of Catholic Democrats. "He's in a class by himself."
However, Krueger said he had misgivings about Chaput. In his view, the archbishop is a political partisan who makes little attempt to disguise Republican leanings.
"He's more than just a culture warrior," Krueger said. As Denver archbishop for 14 years, he "brought the culture war closer to the line that separates politics and religion, and maybe even church and state."
Winters, of the National Catholic Reporter, took it farther. Chaput is "quotable, controversial, and very smart," he said, but, paraphrasing Winston Churchill, he described him as "a bull who carries his china shop around with him, always looking for a fight."
Stephen Schneck, director of the Institute for Policy Research and Catholic Studies at Catholic University of America, took a more temperate view.
"He's distinctive among the American bishops in his ability to make certain kinds of arguments," said Schneck, who called Chaput "an extremely talented prelate."
"But there's a twist," Schneck said. Chaput "sometimes speaks so clearly and with such force that it's more a conversation-stopper than an invitation to discourse, and that might work against his ultimate effectiveness."
In 2006, Chaput drew national attention for his denunciation of legislation to expand the right of Colorado sex-abuse victims to sue their abusers, denouncing its advocates as "anti-Catholic."
"It was about as ugly a political fight as I've been involved with at the Capitol," one lobbyist said.
Three weeks before the 2008 presidential election, Chaput described Obama as "the most committed 'abortion rights' presidential candidate . . . since the Roe v. Wade abortion decision in 1973."
Chaput also was uncompromising when the University of Notre Dame made Obama its 2009 commencement speaker, which the archbishop viewed as a Catholic school's endorsement of Obama's pro-choice stance. "We . . . have the duty to avoid prostituting our Catholic identity by appeals to phony dialogue," he wrote in a column for the Denver archdiocese website.
Krueger, formerly executive director of the liberal church-reform group Voice of the Faithful, opined that some American bishops were taking a "hard stand in the culture war" in order to "restore the moral authority" they lost in the clergy sex-abuse scandal.
But to conservatives such as Lawler and Deal, Chaput is a shining knight.
"He's trying to do his job as a bishop and express things clearly," Lawler said. "There's too much willingness on the part of hierarchy to pull its punches."
Deal said Chaput and New York's outspoken archbishop, Cardinal Timothy Dolan, were animating conservative Catholics who have dropped out of the political process "because of years of disappointment in the hierarchy."
"If I thought [Chaput] was turning people off, I'd tell him. I've got his e-mail," Deal said. "But he's not."
Contact staff writer David O'Reilly at 215-854-5723 or firstname.lastname@example.org.