The Great Will (大いなる理), is the binding force of the universe, from which everything originates, and will eventually return to. Existing beyond time, space and the infinite cycle of transmigration, it is a fully unknowable entity, and the true Supreme Being of the Megami Tensei Series.
Though YHVH, the God of the Covenant, believes to be the One True God, he is in truth only a rogue avatar / aspect of The Axiom, the true source of existence. By creating the physical multiverse, yet simultaneously remaining outside of it, and debasing all other deities as false, YHVH established himself as almighty and supreme. However, he was not behind humanity's creation. Instead, humans were formed by The Axiom itself, and with the Power of Observation bestowed upon them, they would be able to shape their own destiny, through their own beliefs and thoughts.
Though The Axiom rarely interacts with the created world, it will sometimes act on behalf of humanity. On times of great suffering and despair, it will create a Messiah, a human of great power who's Observation can create a path for all mankind.
Verse: Shin Megami Tensei
Name: The Great Will
Classification: Supreme Being, God, Abstract Entity, Binding Force of Reality, The Axiom.
Special Abilities: Omnipotence, Reality Warping, Immortality (Types 0, 3, 4 and 8), Omnipresence, Omniscience, Non-Corporeal, etc
Destructive Ability: True Abstraction (Infinitely superior and transcended to anything else in the Shin Megami Tensei series. Even the true form of YHVH is only an infinitesimally-small fragment of it.)
Lifting Ability: Irrelevant
Striking Ability: True Abstraction
Durability: True Abstraction
Range: True Infinity
Weaknesses: None Notable
List of Equipment: Nothing notable