This is typical of father-to-child home instruction in the Empire, which is the most education on history that most Imperial children get and is mirrored in Imperial propaganda (i.e. all their media), and differs only in the tone and vocabulary used. This would be typical of a doctor to his children, or someone of similar rank, but not part of the Empire's true elite.
What is now called "The Old World" or "The Age of Wonders" ended in a cataclysm, the Azure Flames. What we now know, centuries later, is that this was a divine subversion of an infernal conspiracy's attempt to utilize a mass human sacrifice to power a ritual summoning to bring their master into this world. The ritual failed, the destruction ruined a corrupt civilization, and allowed for the release of a different infernal entity: Legion.
It also put down a judgement on all alive past the age of reason, condemning their corpses to Legion upon death. It also allowed Legion to take any other man's corpse that it slew as the beast it was, but we know now that there was a catch: Legion had to use a human agent and work through him. No agent? Banished once more to realms beyond Man's reach. This is the origin of the villain and traitor known as "The Necromancer", and the source of his immense power.
The infernal conspiracy had its turncoats and sandbaggers. Two of them we now know as The Archmage of Solador, and the Founder of The City-State. We know of the existence of a score of others. These would become, along with The Necromancer, the Dark Lords that dominated the era after the Coming of the Azure Flames known now as "The Wars of the Damned".
The chaos brought about by the rampant sin of our predecessors had one mercy, now also known to be divinely granted, in the transformation of one righteous man into the legendary Ken, father of the race that would allow our Emperor the time and territory needed to gather the remnant of the faithful together into our glorious Empire and build us into a single nation capable of winning our world back from the Dark Lords.
Now, as we near five centuries since the Azure Flames ended the Age of Wonders, the Empire put down The Necromancer and ended Legion's threat. Other Dark Lords hide from the Empire, knowing we are mighty and armed with more than muscle and machines. Their ruinous powers cannot withstand our faith. One by one, we shall put all of them to the sword and burn their blighted lands to ash before claiming them as our own once more. Go forth, my son, and serve the Emperor with all your heart. The Emperor will lead us to victory, to true freedom, and bring cleansing fire to all who defy what is commanded of us.
Note that this is not the actual truth of the Empire of Man. The actual truth is that it is another "Dark Lord", born of the same conspiracy that caused the cataclysm. The Empire deliberately models itself on Warhammer 40000's Imperium of Man, and its own inspirations, and as its technical proficiency increases more things out of those inspirations appear. However, the Empire does have one quirk of its own: it does not have a military- it IS the military; there is no civilian life. Every man is a soldier. Every woman is a nurse. This grants total control over the population under permanent wartime conditions, and permanent subjection to military authority; the religious overtones are the mockery of a true faith, with the Emperor as a Priest-King. While talking a lot about purity and opposition to the supernatural, it harbors a hidden elite with powers of their own. Thus the Empire is, in truth, a militant cult- one that officially celebrates and unofficially hates its allies.