정당한 전쟁 교리: 교황, JD 밴스와 신학적 논쟁

President Trump’s attack on Pope Leo has touched off an argument about a framework for determining when war is justified.

The three most politically powerful men in America — President Trump, Vice President JD Vance and Speaker Mike Johnson — have intensified their criticism of Pope Leo XIV, who has repeatedly spoken about Roman Catholic Church teaching against war and for peace in recent days.

Their fight is not simply political. It is fundamentally religious, as the Republican leaders are now arguing with the pope over theology to support the U.S. and Israeli military campaign in Iran.

On Wednesday on Capitol Hill, Mr. Johnson, who is not Catholic but evangelical, said that he “was taken a little bit aback” when Pope Leo said last week that Jesus does not listen to the prayers of “those who wage war” and that their “hands are full of blood.”

“There’s something called the just war doctrine,” Mr. Johnson said.

After Mr. Vance, who has been a Catholic for about seven years, admonished Pope Leo to be more “careful” if he was “going to opine on matters of theology, the chairman of the U.S. Catholic bishops’ doctrine committee shot back with a rare “clarification” statement about what Catholic “just war theory” really means.

“For over a thousand years, the Catholic Church has taught just war theory and it is that long tradition the Holy Father carefully references in his comments on war,” Bishop James Massa wrote.

To be a just war, he said, “It must be a defense against another who actively wages war, which is what the Holy Father actually said: ‘He does not listen to the prayers of those who wage war.’”

Bishop Massa added, “When Pope Leo XIV speaks as supreme pastor of the universal Church, he is not merely offering opinions on theology, he is preaching the Gospel.”

At its basis, it is a means for people to distinguish permissible killing from illegitimate killing or murder, said Joseph Capizzi, dean of the school of theology and religious studies at the Catholic University of America. There are criteria for how to act morally when getting into a war, and then once you are in it.

It is also an ethic about the “good end” of politics — the things that politics ought to pursue, like stability and peace, which is why we see Pope Leo emphasizing that Christians should be peacemakers, he said.

Just war tradition predates Christianity, as empires like the Romans had their own theorists, like Cicero, he said. The Catholic Church has a specific theological tradition about just war.

One of the Ten Commandments is, “You shall not kill.”

The theology dates largely to St. Augustine, the political theologian from northern Africa who wrote in the early fifth century as northern tribes, sometimes called Barbarians, were invading the Roman Empire.

“There was a kind of presumed pacifism in the first few centuries of the church’s life, but now, the church has responsibilities to society, responsibilities to protect the borders of the nation,” Bishop Massa, the doctrine committee chairman, explained in an interview on Wednesday.

St. Thomas Aquinas further developed it the 13th century, resulting generally in two sets of criteria, one for going to war, and then one for continuing to participate in war, he said.

“We reluctantly will take up arms as Christian believers, if we are facing an aggressor, and it has to be an immediate threat,” Bishop Massa said. “Once we’re involved in the conflict, it’s not as if, OK, then all bets are off, we can do whatever we want.”

Four general principles are outlined in the Catholic Catechism, Paragraph 2309.

The damage caused by the aggressor must be understood as lasting and serious, with concrete evidence, Bishop Massa explained. All other means of ending the conflict must have been exhausted. There have to be serious prospects of success. Proportionality must be considered, as the use of force mustn’t produce evils that are worse than the evil they’re trying to eliminate.

“We need to go back and look at that criteria again,” Bishop Massa said. “I think what we’ll find is that it’s very questionable, the actions that have been recently taken by the United States government.”

People misuse just war doctrine all the time, said Mr. Capizzi, the theology dean at Catholic University.

“Everybody thinks of their reason for waging a war as the right and good reason for waging a war, and this is the point Augustine makes,” he said. “That doesn’t mean all parties are in the right.”

Just war theory actually can determine that one party is in the wrong, he said. He pointed to Russia’s invasion of Ukraine as a clear example, because Russia was the one that crossed a respected international boundary.

“That makes their activity suspect from the perspective of the just war account, in a way that Ukrainian defense against Russian aggression is not suspect,” he said.

Elizabeth Dias is The Times’s national religion correspondent, covering faith, politics and values.