Tainted Letter as a quest objective
Too often people like the followers of the Holy Light scare those curious about true power into thinking they cannot investigate any form of the arcane--not all things from outside this world are evil. Not all entities seek to dominate or subjugate others. If you are powerful enough, those same entities can become the followers.
This is something I would like to discuss more with you. Seek me out in the graveyard on the right side of the abbey.