What is the theme in Iberia: Spanish Travels and Reflections by James A. Michener?

Fear of diversity is a theme in the book. Homogeneity came from the Inquisition. The Inquisition created this culture of fear where everyone needed to be the same to survive. Everyone had to be a good Catholic and a traditional one at that. If new information came in, people turned their heads because they feared learning new things. If they tried to learn something new, or preach something new, they were going against the Church and the state and could be condemned or killed for doing so.