Although Kebos didn't understand why Lady Lisa would order them to disguise themselves as Priests of Light, he didn't care much, as they were still spreading the great name of Master Ange.
Kebos was once a commoner in Ice City, destitute and cold, unable to afford a coffin for his parents, until Lord Ange's arrival.
Lord Ange brought food and the World Tree, not only providing them warmth and satiation, but occasional beetroots to enjoy. When they were sick, someone would heal them, when they died, someone would bury them. Even coffins were available for their deceased parents, rumored to be imported from the human world made of jujube wood.
No longer needing to wander across barren lands in search of their ancestor's remains, this was a prosperous era they could have never imagined. Henceforth, Kebos became a devout follower of Ange, and after various tests, he eventually became a priest of the Undead Temple.