I think you need to work a bit on making this more convincing if you want it to look like a church, perhaps working closer to a reference if you aren't doing that already. Some pointers:
- The walls being covered in those large rocks near the bottom strikes me as strange, since they're usually for outside decoration (imagine having to keep them clean inside a building).
- The benches originate from spawn rooms that are meant to look like changing rooms, so they're very out of place. Any church I've ever seen has more comfortable benches (relatively speaking) with back supports, and are also connected all the way.
- There's no religious imagery at all. The presence of the RED logos makes it look like the church is worshipping RED (which would be silly, as they are a demolition company that fronts a covert organization), and the farm picture strikes me as out of place too.
- The windows in this church are very high up; that may be okay, but I think it'd be nice to have them lower. What isn't so good is that the regular windows and the "R" window are a completely different color, making it look like the outdoors are both a clear day sky and a sunset (or indoor lighting) at the same time.
- The walls and floor seem quite dirty for a church. In my experience they tend to be much more welcoming and well-maintained. A lot of the concrete in TF2 looks like that, so you might have better luck with wood.
- Overall the lighting seems very yellow, which seems unfitting in buildings that tend to use a lot of pure white.
I'd also suggest adding some pillars along the aisle to make it more visually interesting.
EDIT: I also just noticed the random cardboard boxes, and it strikes me as odd that the main room of a church would be used for storage. They tend to have other rooms for that.