(RNS) — While Pope Leo XIV’s new encyclical mostly focuses on AI, it also includes language that suggests that Catholics move past their longstanding reliance on just war theory, offering an assessment of armed conflict likely to spark debate among Catholics and non-Catholics alike.
The Catholic tradition has long drawn on saints like Augustine and Thomas Aquinas to teach that war is permissible in a very narrow set of circumstances — where war is justified as a last resort to respond to damage that must be “lasting, grave and certain.” Per church teaching of just war theory, the war must also be likely to be successful and create less harm than the harm eliminated.
Since becoming pope last year, Leo has been clear he intended to take a firm stand against war. His first words greeting the world after his election were, “Peace be with you all!” in a speech that went on to call for peace that is “unarmed and disarming.” More recently, in his Palm Sunday homily in March, Leo said, “This is our God: Jesus, King of Peace, who rejects war, whom no one can use to justify war.” And his criticism of the Iran war received a strident response from President Donald Trump, to which the pope responded that the Vatican’s appeals for peace were the “message of the Gospel.”
But an encyclical, unlike ordinary speeches by the pope, is one of the most authoritative sources of Catholic doctrine. He writes in “Magnifica Humanitas” — which was released Monday (May 25) and translates to “magnificent humanity” — that, “Today, more than ever, without prejudice to the right to self-defense in the strictest sense, it is important to reaffirm that the “just war” theory, which h …