The Horusians are a subfaction within the Inquisition which consist of members that follow the Thorians' philosophy. The ideals of the Inquisitors that follow this line of belief has waxed and waned since the time of the founding of the Inquisition.
The ideal that is spouted by the Horusians is that the power of Chaos that manifested in Warmaster Horus might be harnessed for the creation of a Divine Avatar or perhaps can serve in the process of transferring the Emperor's soul from the Golden Throne into the body of a living god. This form of thinking is unpalatable to many Inquisitors and has led to the Horusians being considered radicals by everyone except themselves. Though few in number, they are noted for being fanatical in their course. The ranks of the Horusians typically consist of older Inquisitors who are frustrated by the lack of answers provided by the other resurrectionist theories. This is where the danger lies, as the powers associated with Chaos must never be viewed as a quick route to success as that path lies damnation for any who walk down it.
Many Inquisitors view the Horusians with suspicion as there exists a great deal of fear that they are dabbling with the power of the Warp which endangers all around them as well as the Imperium itself. Despite these concerns, most experienced Horusians are well-versed in the perils of the Warp and Chaos, which makes them the most proficient as well as dedicated of Daemon Hunters in the Inquisition. Similar to most philosophies, the members of the Horusians tread a path along the precipice of dedicated service to the Imperium as well as the fulfillment of their research. Most have walked down this path wisely, though not all Horusians have remained faithful - some, like Moriana ten thousand years ago, have succumbed to the temptation of the Dark Powers.