Cult of the Eyeless

The Cult of the Eyeless is a cult of religious monotheistic fanatics who believe that the mysterious entity known as the Unseeing Eye is the one true god of Faerûn and all other gods are made up.

Dogma and Practices
The followers of the Unseeing Eye believe that their sight deceives them and prevents them from seeing the truth about religion: the Unseeing Eye is the only existing god and all the churches on Faerun want to hide this fact. In order to be able to "see" the truth, potential followers are requested to pluck out their own eyes as a test of faith. Should the cultist survive, they are gifted with a magical sight by the Unseeing Eye.

The ones that do not survive the procedure are thrown in a dark pit to presumably feed the beholders in the caves below.

Leaders
Gaal appears the be the head priest and prophet of the cult. He is able to cast Priest spells, though it is not clear if they are actually granted by the Unseeing Eye or another deity.

At the end, the Unseeing Eye itself, the instigator of the cult, is revealed to be nothing more than a powerful beholder.

Enemies
The cult is at odds with all the churches on Faerun who wish to destroy it and expose Gaal as a fake prophet.