Honestly though, sermons would be very easy to provide reliable public-domain training material, seeing as millions have been preached, and thousands published

Honestly though, sermons would be very easy to provide reliable public-domain training material, seeing as millions have been preached, and thousands published in the last two millennia. There are whole books and archives full of them. Just concentrate on the canonized dudes and you can avoid any heresies. If a religious LLM were trained on reliable data, this would not necessarily be a bad thing. Many pastors don't like composing homilies and some, in fact, used canned ones that come from a book or a subscription service anyway. It is definitely not considered plagiarism for a pastor (or a rabbi or an imam or a lama) to borrow a very holy, engaging homily. My pastor did it with Fr. Robert Barron. Good stuff.