Catholicism is but one denomination of Christianity as a whole. If you took Islam apart, you could say there are more Catholics than Shiites. Christians as a whole still outnumber Muslims as a whole. But that won’t last long because of the respective birthrates.
what’s the birthrate in South America and Africa?
It is because of the missionary efforts in the countries of Africa and in a special way in Asia, for example because of lot of that church has to be underground because of government oppression they say China could have up to 100 million Christians. That is the wild card.