In the Footsteps of the Dead Gods
What we'll be calling Dungeon World is known simply as "the World" to its denizens. It is a place of great wonder and terrible danger, in which most people simply try to survive. It is also a place where magic and wonder (and more than a little weirdness) are ever-present and the Dead Gods loom large.
The Dead Gods are generally believed to be ever watchful, even after their mutual destruction. Most humans align themselves with one of the gods: Followers of Lissa believe in law and order; followers of Rolgar believe that life is a balance of fairness and individual freedom; and followers of Califrax believe in personal gain over all else. Even those humans and demi-humans who do not profess to follow one of the Dead Gods are usually recognized by this system of alignment.
As far as the demi-races go, each has an association to one of the Dead Gods, regardless of individual alignment: Califrax is the "Patron of the Elves," whose inherent magical affinity makes them naturally inclined to follow the path (see below) of He Who Knows; Rolgar is known as "God of the Dwarves," presumably for their shared love of combat; and Lissa is the "Mother of the Small Folk," as she took an active part in nurturing and protecting Halfling society.
There are those, however rare, who believe not only in aligning themselves with the Dead Gods, but in following their path. These people (be they human or demi-human) believe, for one reason or another, that their purpose for living is to seek adventure. Regardless of their alignment (or lack thereof) to any god, these people choose to embrace the philosophy and life of the adventurer.
Avoided - or even shunned - by most "normal folk," adventurers lead lives of great danger and, sometimes, even greater reward.
The Lunatic Fringe
The Dead Gods are not the only recognized cosmic forces in the World. A small pantheon of deities, demi-gods and legendary heroes continues to grow. Most of these are real historical figures, often adventurers, that have achieved mythical status. Adding their name to this list of the worthy is the driving motivation of more than a few adventurers.
No discussion of the religious and philosophical aspects of Dungeon World would be complete without at least a mention of The One-Hundred-and-Thirty-Seven Adherents to the Way of the Cryptic Egg. Be it scholar, artist, layman or some other walk of life, members of the philosophical cult of The One-Hundred-and-Thirty-Seven come from diverse backgrounds and social strata. They are firm proponents of adventuring (whether or not they are themselves adventurers), but they believe that it must be accomplished according to "The Old Ways," as outlined in the Adventurer's Codex, one of the Tomes of Legend brought to the World by the Dead Gods.