I wrote a long, helpful, positive, supportive, constructive review before my computer crashed. Now you get this:
Sound, art, and mechanics were good. Thoughtfulness is good; needs to be more intuitive.
Music is too uncomfortable. You play this for a decent while, so add a different track or something - make it less difficult to listen too.
Level-up mechanic is ridiculous. I don't know if you need the exact faith value shown to level up (if yes, change it for the love of your evil god) or if it just glitches but I've consistently gotten several hundred faith over the limit and not levelled up. To give context, my next point is about discernibility; I can't tell what's a seven or a one on the 'reach x faith' so if there ever was a one in these - know that I went up to at least nine-hundred before I remember levelling up.
You need a middle-ground in effectiveness and cost between the high acolytes and the ghouls you don't have for two minutes. There shouldn't be so little incentive to play the game on idle. Maybe add a tutorial feature. The followers' order isn't intuitive. Just order it most-to-least costly.
I know f*ck-all about making a video game so I might have just told you to scale a sheer cliff face with one arm, but there's my two cents.