Another way to ask that question would be: Which European country was most active in exploration and expansion into Africa in the 15th century. The answer: Portugal. Along with their commercial interests, they also brought their religion with them. The spearhead of the Portuguese expeditions to Africa was Prince Henry, dubbed "the Navigator." He didn't actually go sailing, but he was the driving force behind the Portuguese campaigns to go spread their influence--and their Catholic Christianity--to other parts of the globe.
