|“|| In the beginning we lived as thieves,|
Stealing fur and fang of beasts for survival
|— The Hammer Book of Tenets|
The Master Builder (aka "The Builder" or just "Builder"), is the principal deity of the Order of the Hammer and its offshoot, The Mechanists (though towards the end of that sect its leader Karras was considered — and considered himself — equal to or above the Builder). He is the god of innovation and order and is the primary force opposing the Trickster, the god of nature and chaos. According to the Hammerites, the Builder taught people to use the hammer and other tools so that they could protect themselves from their dangerous natural environment and use technology to develop their civilization. The Book of Hammer was written based on his deeds and assertions. It is the main compendium of laws and rules for the Hammerite Order. To the Hammerites, the most blessed symbol of the Builder is the Hammer.
The Builder's doctrine teaches that the nature should be used as a resource for creating material benefits, such as the advancement of civilization and the construction of factories and other buildings. Blindly following this doctrine to its extreme may be dangerous. Followers may be led to destroy the entirety of nature: mankind itself along with all organic life. This was demonstrated by Karras, who, seeking the Builder's favor, attempted to destroy all biological life in Thief 2.