Fundamentals of faith could provide infinite healing. While this doesn't personally bother me because of the small amount, there are alot of people irked by something like that. May I suggest adding a clause that limits the use of healing cantrips?

You refer to devotionals as mysteries when you mention the save.
I really like devotionals though, mainly because they are based off of shadowcasting (which has always been a favorite of mind).
And I'm goint to ask the same thing as eledragon, are you going to use spells already made, or are you going to create your own devotionals? (I hope you create your own, as it would add even more unique flavor to thh class).

Do you only have access to devotional feats when you gain bonus feats? May I suggest allowing exalted feats? They are a bit powerful, but...