Whenever a Catholic runs or is nominated for public office, he or she has to endure a now-familiar vetting process revolving around one thing: abortion rights. To make progressives happy, candidates must follow the Mario Cuomo script of “I am personally opposed but I will not impose my will on other people.”

But they also have to be careful not to alienate conservatives by downplaying their faith and morality. It’s a very hard needle to thread, and a lot of people fail miserably at it. Rendering unto Caesar sometimes means denying God, and vice versa — someone’s right not to have religious beliefs imposed on them must be balanced against another person’s right to practice his or her faith.

Americans saw this conflict play out for the umpteenth time last month, when a Catholic priest in South Carolina denied Joe Biden communion. The former vice president was attending mass at Saint Anthony Catholic Church in Florence, and Rev. Robert Morey denied him the Eucharist, stating later that a “public figure who advocates for abortion places himself or herself outside of Church teaching.” He added that he would pray for Biden.

For his part, Biden refused to dwell on the incident other than to say “I’m a practicing Catholic, I practice my faith” and that this was his personal life.

Social media lit up with people who were angry that Biden had been publicly shamed. Some felt that the Reverend Morey was out of touch with changes in the church, and that support for abortion rights was not necessarily a moral evil.

But Canon Law -- specifically Canon 915 of the 1983 Code -- is clear: “Those…who obstinately persist in manifest grave sin, are not to be admitted to holy communion.”

Abortion is still considered one of the gravest sins in the church. Joe Biden is a strong proponent of Roe v. Wade, in June dropping his support of the Hyde Amendment and its ban on federal funding of abortion.

That being the case, the church is right to deny him communion. As I said before, some think this is intolerant. Jesuit Father James Martin tweeted in Biden’s defense: “Denying Communion to politicians, Democrat or Republican, is a bad idea. If you deny the sacrament to those who support abortion, then you must also deny it to those who support the death penalty. How about those who don’t help the poor? How about ‘Laudato Si'? Where does it end?”

But Pope Emeritus Benedict, still active, had the answer: “Not all moral issues have the same moral weight as abortion and euthanasia….there may be a legitimate diversity of opinion even among Catholics about waging war and applying the death penalty, but not however with regard to abortion and euthanasia.”

That pretty much settles it from a religious perspective, coming as it does from a Pope. Biden was rightfully denied the sacrament. Rev. Morey was not inappropriately imposing his beliefs — he was following the letter of the church.

Archbishop Charles Chaput, one of the most eloquent observers of religion in the public sphere, provides a much richer view of how to reconcile public and private selves than Cuomo’s “I will not impose” standard:

“The church claims no right to dominate the secular realm. But she has every right — in fact an obligation — to engage secular authority and to challenge those wielding it to live the demands of justice. In this sense, the Catholic Church cannot stay, has never stayed, and never will stay ‘out of politics.’ Politics involves the exercise of power. The use of power has moral content and human consequences. And the well-being and destiny of the human person is very much the concern, and the special competence, of the Christian community.”

Chaput’s gracious stance far exceeds the rank hypocrisy of those who want to keep religion out of politics, and yet lord politics over religion. If you don’t want us telling you how to write your laws, don’t tell us how to manage our sacraments. Deal?