If you want to know what was in his head read his Book, READ THE BOOK! There are many good translations available. Moslems will uniformly declare to you that all translations of the Koran are merely unreliable “commentaries” or outright lies. There is a good reason they need to say that. Read the book.
I used to work with quite a few Koreans some years ago and most of them attended Korean Methodist or Korean Presbyterian churches and a few were Catholic. South Korea has a LOT of Christians. I greatly enjoyed their company. They were all deeply patriotic Americans, worked hard and made a point of assimilating. Pretty conservative by nature.