Conversation so far:
What was the Chautauqua circuit?
Bryan was the most popular speaker on the Chautauqua circuit, delivering thousands of paid speeches on current events.
What are some examples of the topics that he spoke about?
He mostly spoke about Christianity, but covered a wide variety of topics.

Question: What was his topic on Christianity about?
Self-contained rewrite: What was William Jennings Bryan speech on Christianity about?