What is collective noun of churchgoers?

There isn't a single, widely accepted collective noun for churchgoers. However, here are some options you could use, depending on the context:

Formal:

* Congregation: This is the most common and generally accepted term for a group of people attending a church service.

* Assembly: This term emphasizes the gathering of people for a common purpose.

* Body of Believers: This term emphasizes the shared faith of the group.

Informal:

* Group

* Gathering

* Fellowship

* Parish (this specifically refers to the community associated with a particular church)

You could also use more descriptive phrases like:

* The faithful

* The worshippers

* Those attending the service

Ultimately, the best collective noun to use will depend on the specific context and the tone you want to convey.