I'm pretty much in the same boat as others. I figured out the controls by looking at the game's page, but even then after interacting with the white square I was quite lost on what to do next. I tried going back to the big church but was unable to climb back up the vertical shaft (one of the ledges is so narrow that it wasn't registering me as on the ground so i wasn't able to jump off of it), so...
One suggestion I can make is to add some dampeninging to the camera, it was a little disorienting to have the camera moving up and down to mirror your player's movements.
Anyway, the aesthetics were qutie nice, the writing had the right tone for the atmosphere you're presenting. The effects on the demon/exorcist attack and dash were also nice. It definitely has a classic vibe to it, so if you want to continue working on it the presentation and writing are already going in the right direction. Good luck!