We don't know if Choi Jong-yul is a religious person, but if he happened to stop at a house of prayer in an oasis town along his route, chances are it was a mosque. Overwhelmingly, the people of northern Africa from Mauritania to Sudan are adherents of Islam.
The McKinley Internet Yellow Pages are an excellent guide to on-line information about the world's religions. A good place to start is the 4-star Web site Facets of Religion. You can follow up by searching the McKinley Magellan Internet Guide on line.