To be even more picky, many Protestants also believe in the 'one holy catholic and apostolic church' and so authentically see themselves as 'catholic'. Catholic is a description basically meaning all-embracing. Roman Catholicism is a branch of Christianity against which historically many 'protested' during the Reformation. To add to the mix, there are plenty of people who would describe themselves as a Catholic (or protestant,though perhaps to a lesser extent - cf Northern Ireland), who are so culturally rather than by religious conviction.