Why do Priests exist?

[hcobb]

My setting is that the Wizard's Guild is thoroughly agnostic. They see the magics performed by priests and shamans as dangerous shortcuts that shortchange the student's ability to eventually learn the full breadth of magic in exchange for learning prayers to higher powers that most likely don't exist. Those few tricks the priests have that aren't in the schools of magic either aren't generally useful (being limited to religious rituals of dubious value) or involve some trick that it's not worth the effort to research.

Most religions regard the Wizard's Guild as a bunch of misguided souls who are going to hell and who commune with dangerous lower powers like demons.