Earlier this year, pastors across the United States began warning their congregations about a disturbing new problem: videos that looked and sounded like them, but were not.

Artificial intelligence was being used to impersonate religious leaders, putting words in their mouths and exploiting the trust they had spent years building with their congregations. Catholic priest and podcaster Mike Schmitz, who reaches more than a million people on YouTube, was among those targeted. Fake versions of him appeared online delivering messages he had never recorded and directing followers toward fraudulent solicitations.