Final answer:
The dominant religion in South America is Roman Catholicism, with Brazil having the largest following. The current Pope, Pope Francis, is from Argentina.
Step-by-step explanation:
The dominant religion of South America is Roman Catholicism. Reflecting the region's history as part of the Spanish and Portuguese empires, Roman Catholicism was firmly established and remains prevalent to this day. Out of all South American countries, Brazil has the most Roman Catholic followers. Regarding leadership within the Catholic Church, the current Pope, as of my knowledge cutoff in 2023, is Pope Francis, who hails from Argentina. This aligns with the strong Catholic presence throughout much of South America, which was imparted during the era of European colonization, particularly by Spain.