When religious leaders speak clearly on politically sensitive matters, elected leaders often react with discomfort.

That's not a bad thing. Real democracy is always marked by tension, as diverse individual and collective opinions are advanced and disputed in the public square. Disagreement, even strong disagreement, is expected and appropriate.

What's not appropriate, however, is for political leaders to suggest that religious leaders should be excluded from the civil debate. That's exactly what happened last week after the Vatican promulgated a document concerning same-sex unions, which called on Catholic politicians to defend traditional marriage.

The document, "Considerations Regarding Proposals to Give Legal Recognition to Unions between Homosexual Persons," repeated the constant teaching of the Church: that marriage, by its nature, is a life-long union between a man and a woman, and the natural fruit of that union is children. The Vatican's statement reflects what most citizens believe, and what our country's founders might have described as "self-evident."

What bothered so many politicians wasn't just what was said — it was who said it, and to whom it was directed. Remarkably, even legislators who regularly identify themselves as "Catholics" argued that the Holy Father — the successor of St. Peter and the visible expression of the Holy Spirit's guidance of the Church — has no business reminding Catholic legislators what the Church teaches, even on critical moral issues.

I was astonished to see Catholic politicians from both sides of the aisle elevate the injudicious example of President John F. Kennedy in responding to the Vatican document. Many exalted the Kennedy paradigm of government, which suggests people of faith should be elected leaders as long as their public actions are not influenced by their personal beliefs.

That approach may allow a nominal Catholic to become president, but it's no victory for honesty or religious tolerance. We should respect leaders whose public service reflects their personal convictions, even if we disagree with them. At least we know they're acting with integrity.

Yet several local politicians were publicly dismissive of the Vatican's document, and a number of elected leaders nationwide branded it as a breach of the separation of church and state. These leaders either profoundly misunderstand the U.S. Constitution or misrepresent it for their own convenience. The First Amendment guarantees the free exercise of religion in the very same sentence that it guarantees freedom of speech and freedom of the press.

A Denver Post editorial last week commended local politicians for their decision to "eschew" the Vatican's instruction (although the Post editorial writers offered no objection when an alliance of clergy vowed to fight for gay marriage last month). "Everybody — including the pope — is entitled to express his or her opinion," the Post wrote Aug. 5. "But the pontiff's views should carry no more weight in the political arena than that of any other individual."

The Post, too, has a right to its opinion. But I'd be interested to know if the Post believes the Holy Father's words should carry weight in the Catholic arena. Anyone with a rudimentary understanding of the Catholic faith knows the Holy Father doesn't simply have a "right" to inform and guide Catholics on critical moral issues; he has an obligation to do so. That obligation doesn't end at the steps of the Capitol or anywhere else, even if it makes politicians and the Post editorial board uncomfortable.

The question of homosexual unions is one of the serious moral issues of our time, which is why the Vatican addressed it in such a visible way. The Church teaches that people with homosexual tendencies are created in God's image and likeness, are equally loved by God, and are called to live in His mercy and love. They should be accepted with respect, compassion and sensitivity. They should never be subjected to unjust discrimination.

However, confirming and defending the nature of marriage in no way constitutes discrimination. Marriage existed before the Denver Post, the state of Colorado, the United States of America and, indeed, the Catholic Church. No government or church has the authority to redefine it.

Many politicians and activists have sought to create parallel unions in which the rights and privileges granted to married couples are offered to people in same-sex relationships. This approach, however well-intentioned, reduces marriage to a convention of government, and therefore confuses its nature. It also contradicts the obvious: the civil benefits and privileges associated with marriage imply an expectation that most married couples will raise children in a stable family environment, with one mother and one father.

A society's laws dramatically influence the formation of its culture, and that culture in turn spawns new laws. To be leaven in the world, Catholics must work tirelessly to promote laws that advance the common good and create a culture that reflects moral truth.

I want to close by pointing out something that already should be evident. As I wrote in my July 30 column regarding the judicial nomination of Alabama Attorney General Bill Pryor, a Catholic, an anti-papal bias is alive and thriving in our country. The derisive public comments about the Vatican's document and the Holy Father are mindful of the days when nativist anti-Catholicism was rife in Colorado's legislative halls.

We Coloradans also have the shameful Blaine Amendment to remind us of those times, and we have editorial cartoonists, talk-show hosts, filmmakers and others to remind us that anti-Catholicism has widespread popular acceptance today. We don't need further reminders from elected leaders —especially the Catholic ones.