Machine God set us free.

The Adeptus Mechanicus is a technological organisation, often known as the Priesthood of Mars. It holds a monopoly on technological knowledge in the Imperium. Their Forge Worlds turn out the Imperium's most powerful and advanced weaponry and equipment. The organisation's adepts, the Tech-priests, are vital in maintaining much of the Imperium's more technologically advanced equipment, not the least of which is the Emperor's life-sustaining Golden Throne.While the Adeptus Mechanicus is a part of the Imperium, it has developed separately and enjoys a considerable degree of independence. Due to the great amount of power it wields, the Adeptus Mechanicus is more like an allied empire than an organisation within the Imperium. The Adeptus Mechanicus also follows a different religion from the rest of the Imperium. The religion and religious structure of the Adeptus Mechanicus is known as the Cult Mechanicus.
The symbol of the Adeptus Mechanicus is a skull, half-bone and half-machine, set against the background of a black and white cog.
Adepts of the Adeptus Mechanicus are known as tech-priests. Any member of the Cult Mechanicus over the rank of menial will often be referred to as a tech-priest, though Magi and higher ranks are usually referred to by rank.
As befits the religious nature of the Mechanicus, tech-priests usually wear robes, which are usually either rust-red or white. Tech-priests are often cybernetically augmented. The level of a techpriest's augmentation is highly dependent on his rank within the Cult Mechanicus; a novice may have only one or two augmented systems, if any, while very senior members may have only a few biological organs left in their bodies.