Well they where the Sol Divisive. These are a sub-spcies of the vex that you see almost ALWAYS worshiping. Like in the final mission of the original Destiny story, they where worshiping their god. Their belief is that worshiping equals power. Also that idea is based off Sword Logic. This was learned from Quira Blade Transform who told these vex to woriship. I think these worshipers worship a worm gods heart.