Roman Catholicism is the largest Christian church, with adherents primarily in South America and Southern Europe. It differs from Protestantism in its emphasis on tradition, ritual, and the authority of the Pope. Key Roman Catholic doctrines include papal infallibility, transubstantiation in the Eucharist, purgatory, and veneration of Mary and saints. The religion's teachings and practices have evolved over time, becoming less rigid after the Second Vatican Council addressed relations with the modern world.