Simon Willison points out that Pope Leo XIV's encyclical, Magnifica Humanitas, attempts to bridge centuries-old Catholic social teaching with modern AI ethics. While the document’s emphasis on human dignity and justice is commendable, its effectiveness hinges on whether it can influence secular AI development practices. The encyclical’s focus on interpretability and cultural biases in AI systems is timely, but its recommendations may struggle to gain traction outside religious circles. The Vatican’s foray into AI ethics could spark broader dialogue, but its practical implementation remains a challenge.