noun
Roman Catholicism
Refers to the Roman Catholic Church and its faith, distinct from other Christian denominations.
ローマカトリック教は世界最大のキリスト教の教派です。
Roman Catholicism is the largest Christian denomination in the world.
キリスト教 is the general term for Christianity, encompassing all denominations including Roman Catholicism.
From English 'Roman Catholic' plus 教 (religion/teaching).