Also known as "angel worship," however this is inaccurate as any good outsidere can be worshiped. While the celestials themselves cannot grant spells, good deities who agree with the celestial's motives and teachings will grants spells through the celestials. The worship of celestial beings commonly directly opposes the denizens of the lower planes and their followers.
Celestial Knowledge: You have a limeted form of alignment detection. You have studied the aspects of what makes a creature evil. As a full-round action you may make a sense motive check to determine if a person is evil or not (DC = 10 + 1/2 creature's HD + its Wis modifier). The creature may use its bluff check as the DC as an immediate action if it is higher. If successful you know the creature is evil or not. Normal spells that block alignment detecting divinations also blocks this ability. IN addition, you gain a +1 bonus on Knowledge (Planes) check to identify outsiders.