What is a group of Catholics called?

Answer 1

For a region, it is called a vicariate.

Catholic AnswerA group of parishes could be a diocese, which would be a large group headed by a Bishop. The diocese is divided into deaneries which are headed by a Dean or Vicar Forane, and are groups of parishes.

Answer 2

A group of Catholics would be called a group of Catholics unless you are thinking of something specific, like a congregation, or a pilgrimage, or a class. You need to be more specific. There is no common plural noun that I know of like gaggle for geese or herd for cattle.

Answer 3

a diocese