Proposed features/Church hall
|Definition:||A building operated by a worship community primarily for activity among members of the congregation|
|Rendered as:||Small religion symbol (cross, star, etc) inside a house|
|The proposal has been obsoleted by the frequent use of amenity=community_centre which can be specified with community_centre=parish_hall plus religion=*.|
To mark buildings that are not general public community centres but function in a roughly similar way for members of an individual church congregation.
Many worship congregations have a non-worship space for committees, vestry meetings, social events, fundraising events, religious education, office space, and/or as a backup or overflow worship space; but such spaces are not primarily worship spaces, hence amenity=place_of_worship is not appropriate. In some cases the social hall is in a basement of the worship space or otherwise part of the same building, in which case it is considered part of the larger worship space, but the particular use-case for this tag is when there is a separate building, e.g. next door or across the street from the main church building. Other tags are not really suitable.
In Germany, these are quite frequent, at least for Christian communities, and are usually called Gemeindezentrum or Gemeindehaus (see Gemeindezentrum (Religion) on de.wikipedia.org).
Alternative: Community centres are public locations where members of a community tend to gather - this can be a religious community as well. Therefore, amenity=community_centre is perfectly suitable, which can be further specified with community_centre=parish_hall or similar. As the tag is religion-neutral, it can be further specified with religion=*.
Discussion on the question board help.openstreetmap.org: How do I tag a German "Gemeindehaus" (parish hall)?