Here's why:
* Historical Context: The Catholic Church, the largest Christian denomination celebrating Mass, developed in the Roman Empire, where Latin was the official language.
* Universal Language: Latin became the language of scholarship, religion, and government across Europe, making it a suitable choice for a universal liturgical language.
* Tradition and Authority: The use of Latin in Mass became deeply rooted in tradition, symbolizing the Church's continuity with its past and its authority.
However, in the 20th century, the Second Vatican Council (1962-1965) encouraged the use of vernacular languages in Mass. This resulted in a gradual shift towards local languages in many parts of the world.
While Latin remains the official language of the Church and is still used in some ceremonies, the majority of Catholics now celebrate Mass in their native languages.