meaning - "Parishioner" vs. "congregant"

I've always thought that the words parishioner and congregant meant the same thing and could be used interchangeably within the context of someone who attends a place of worship. Are there any differences in meaning between these two words or appropriate usage for each?

Answer

Parishioner and congregant refer to members of a particular local faith community. The requirements for membership, of course, vary considerably, but for the most part, simply attending services at a church does not make one a parishioner or congregant of that church any more than visiting a country makes one a citizen of it.

Sectarian considerations govern which is the more appropriate term.

Parishioner is older by a good measure. A parish is an ecclesiastical territory, a section of an episcopal see (e.g. a diocese or archdiocese). Traditionally, any inhabitant of that territory would have been expected to attend services at the local parish church, and all would have been parishioners. The Catholic, Anglican, and Orthodox churches remain organized in this manner, but the term "parish" is used even by some denominational bodies without episcopal administration, so making the members parishioners.

Congregant is broader, in that it refers to the regular members of any local congregation. That local congregation may be a parish, but it might also be a local church or meeting house of a tradition that does not use the term parish, such as the Baptists or Mormons— or for that matter, Muslims or Jews.

To refer more generally to those attending services at a particular time, you could simply say worshippers or attendees; for all adherents, there are a variety of terms employed, such as the brethren or the faithful, or the more mundane churchgoers or the observant; communicants captures the sense of those in communion with the Church as opposed to outsiders.