I've mentioned it before, and I'm sure I will again, but, as much as there's a reason why I reject Christianity, there were also a lot of good things. Churches have governing bodies (with varying degrees of democratic representation) that guide the ministry (preaching and actions) as well as managing logistics (building maintenance, accounting, etc). This provides opportunities for self-governed collective action.
Quakers are the most radical in terms of this, and are basically anarchists. Quaker circles often meet at people's houses and can be as small as 3 people. There is often no leadership. A Quaker service could easily just be everyone sitting in a circle and someone talking at one point.
I grew up in a Presbyterian church, and one of my first jobs (at 11 or 12) was landscaping there. Within the church there were a lot of different trades, which meant that you could volunteer time and learn basically any kind of maintenance. Basically everything that needed to be done was done in-house. This also meant that if you needed a plumber, an electrician, etc, that you could pick one from within the church.
I remember painting the church, learning how to paint, with a bunch of other members of the congregation at a work party. I also remember being volunteered for child care during choir. There were a few rooms around that were used for different things, such as music practice. But these rooms could be made available for any type of community activity. This can actually include community organizing. In fact, Seattle GDC was offered an occasional space for organizing in a church (we didn't take it, but appreciated the offer), and that same church hosted a lot of other community events. I actually went to a queer relationships skills class once hosted in a church, which was great.
What I'm saying is that churches often act as a kind of parallel society up-to-and-including acting as dual power structures....