Spirit represents a character's ability to withstand mystical stress and is also a reflection of the character's general spiritual resolve.

APs Benchmarks
1-2 The individual can withstand average life experiences with two or three major crises.
3-4 The person's Spirit is equivalent to that of an individual who can weather an assault on his or her core beliefs. Heroes with this: Ice, Changeling, Desaad, Checkmate Knight
5-6 This person is so secure in his or her beliefs that he/she is willing to die for them. Most heroes fit this Heroes who have this: Huntress, Fire, Booster Gold
7-8 The individual is capable of enduring several major crises without loss of resolve. Heroes with this: John Constantine, Deadman
9-10 The individual possesses a fortitude that cannot be altered even by the blackest life experiences. They can withstand the mystical assault of an experienced sorcerer. Heroes with this: Batman, Wonder Woman, Doctor Occult, Mister Miracle
11-12 This person can easily cope with extraordinary phenomena and knows no true fear. This is usually a qualification for entry into the Green Lantern Corps. Heroes with this: Zatanna, Brother Blood, Green Lantern (Hal Jordan), Arion, Sinestro
13-15 This individual can endure several attacks from a master level sorcerer and traumatic supernatural phenomena routinely. Heroes with this: Amethyst, X'Hal, Zantanna
16-18 This person's spiritual resilience is equivalent to that of a god-like mystical being. Heroes with this: Darkseid, Ares
19-21 At this level the Spirit remains strong even in the ravages of a hostile environment such as Hell or Qward. Heroes with this: Lords of Order and Chaos
22-24 The Spirit can withstand an extended battle with a major demon. Heroes with this: Doctor Fate (Nabu)
25-27 The individual can resist the attack of an entity-level mystical force. Heroes with this: Trigon
28-30 The person is spiritually pure, or invulnerable, a condition attainable perhaps only in a state of nirvana. Heroes with this:Death