The Church of the Lightbringer
According to holy scripture, the darkness before creation was filled with demons. A deific figure (that bears no proper name) came and brought light to this darkness. With that light came the material world and the passage of time.
The demons were angry. They did not like the material world encroaching on their domain. And they especially did not like time, because they suddenly could grow old and die. They vowed to destroy the light and the world.
In response, the deity created humans and gave them dominion over all the world so that they might stand as defenders of creation. In order to instruct humanity, and to ensure that it would never forget its purpose, the deity chose the purest, kindest, most virtuous child he could find. He placed a fragment of himself in that baby. This woman, known properly as Our Holy Luminous Matriarch, became a prophetess. (A host of other names developed with her legend: The Shining Lady, The Brightest Blossom, Our Effulgent Mistress of Resplendence, and so on.)
The Luminous Matriarch traveled the land, teaching the wonders of the deity that brought us light, and the demons that wish to corrupt and destroy us. She took on disciples that spread out so that her word could reach all corners of creation. As all things must, she grew old and died.
Her words and teachings live on in the holy scriptures. (The Forty Two Incandescent Volumes, consisting of 8,212 pages of stories, verse, and rituals.) Humanity, the chosen and most gifted of the intelligent races (at least, according to scripture,) banded together under Her litanies to form The Empire and conquer the world.