Consensus reality is the agreed-upon concepts of reality which people in the world, or a culture or group, either believe are real, or treat as real.
Bureau File[]
As was explained there are two things that have positivity been identified as belonging to a consensus reality in our continuum. Religion, and the after life; and Magic.
Magic[]
In the past the magic level, that is the amount of magic that could be accessed depended on the belief that you could access magic. The stronger the belief, the stronger magic really was. The connection of Greyhawke has broken this mechanism. Full Breakout is imminent.
Religion[]
Sufficient belief in the divinity of a thing or person can result in that person or thing becoming divine. We were not given a threshold. However, Elvis was resurrected to keep him from becoming a god.
The variety of the Enlightened throws a considerable "light" on this subject. "There are many paths up the mountain" as we are told. Hell is the place you go when you condemn others to it.
In short, when a sufficient number of people see something as "god" it becomes one, a segment of the Throne, or the creative force of the universe. We are informed that this does exist. Gods as we understand them are life's attempt to deal with this creative force.
Outsider gods are possible, such a the Greyhawken Primal beings beings or things like Dagon. The origin of that latter dark power is unknown, and perhaps unknowable. The Greyhawken gods come from Greyhawke. Jedi, an outside belief has also proven to work here. Both on Earth and the World of Vich Ar.