ST. LOUIS — In his three years as St. Louis archbishop, the Most Rev. Raymond Burke has taken on a presidential contender, a pop star, Missouri politicians and even parishioners.

American bishops regularly speak against public policies that run contrary to Roman Catholic teaching, but Burke stands out for his hard line taking on those who oppose church teachings, no matter how high-profile or popular they are.

"I know I have to teach. I know I have to be clear about the church's position," Burke said. "If that means that national media takes an interest in it, then that's something that I have to accept. But that's certainly not my object in my activity."

Burke set off a national debate in 2004 when he said he would deny Holy Communion to presidential hopeful John Kerry because the Catholic Democrat supports abortion rights. Only a few other U.S. bishops went as far as Burke; most said they opposed using the sacrament as a sanction.

In April, Burke resigned as board chairman for the Cardinal Glennon Children's Foundation because of a benefit-concert appearance by singer Sheryl Crow, who supports abortion rights and embryonic stem cell research.

The archbishop, a genial-looking man with a soft conversational voice, said he must serve as a moral guide.

"The most pressing issue is the secularization in society," Burke said. "The church finds herself more and more in a prophetic role of calling into question trends in society, for instance, practices like widespread procured abortion, and now, human cloning and embryonic stem cell research."

Burke, 58, came to St. Louis after years in Rome. A graduate of the Pontifical Gregorian University in Rome and a student of canon law, Burke spent five years in service to the highest court in the church, the Supreme Tribunal of the Apostolic Signatura. In 1995, he was installed as bishop of La Crosse, Wis., then in 2004, was elevated to St. Louis, home to 550,000 Catholics.

Burke said he has been surprised by the strong reaction to his declarations. Kerry has said he shares the church's opposition to abortion, but did not feel it was appropriate to legislate personal religious beliefs.

"To me, it didn't seem like anything very radical to say that a Roman Catholic who persists in a public way in fostering legislation that permits procured abortion should be denied Communion," Burke said.

"The church in her whole history has always understood this, that if you publicly persist in a gravely sinful act, that you should not present yourself for Holy Communion, and if you do, because of the public nature of it, you should be told not to."

Before weekday Mass at the Cathedral Basilica, the ornate crown jewel of St. Louis' Catholic churches, Bryanne Whitney, 22, said there's much more to Burke than his statements that brush up against politics and pop culture.

He calls Catholics to strengthen their faith, to listen to God and follow the path God has set out for them, she said.

"I think he's on the straight and narrow," she said. "He's consistent, and he upholds the church's teachings."

Burke also has his critics.

In 2005, the archbishop excommunicated the six-member board of St. Stanislaus Kostka, a traditionally Polish parish, after it refused to end an arrangement that dated to the late 19th century giving it authority over parish finances.

Burke also excommunicated the Rev. Marek Bozek, who was brought in by the parish.

Bozek said the archbishop is a good man, but inflexible.

"For him, I think compromise is a dirty word," Bozek said. "Unfortunately, the church is moving from having a dialogue into a monologue."

Burke has not commented on specific candidates in the 2008 presidential race. Four of the Democratic contenders and three of the Republicans seeking the nomination are Catholic.

Last month, Rhode Island Bishop Thomas J. Tobin called statements on abortion by former New York Mayor Rudy Giuliani, a Catholic Republican, "pathetic" and "hypocritical."

Giuliani has said he's personally opposed to abortion, but believes women should be able to decide for themselves whether to terminate a pregnancy.

Burke said he will continue to speak out about church teaching, even when it sometimes means that he must "say difficult things to the culture in which we live."

He knows not everyone will accept the message.

"You cannot be a good Catholic and be in favor of procured abortion or be in favor of embryonic stem cell research. It's just not possible, and so if by teaching what the church teaches, people see that as polarizing, I think they are mistaken."