The two organizations fought for the influence of Sanctuary's people in what will be known as the Sin War.

In retaliation, Inarius created his own sect, the Cathedral of Light. That struggle has now spilled over into Sanctuary - the world of men.

Since the beginning of time, the angelic forces of the High Heavens and the demonic hordes of the Burning Hells have been locked in eternal conflict for the fate of all Creation. Thankfully, Inarius would notice the plans of the Prime Evils. Diablo: The Sin War, Book 1: Birthright Publisher's Summary. Unfortunately, the Vizjerei or Spirit Clan of Mages would accidentally contact demons in the guise of 'spirits.' This would lead the Prime Evils to establish the Cult of the Triune dedicated to their worship, disguised as beings of good. In contrast, the Sin War Trilogy and Book of Cain establish that the term was in use long beforehand, not long after the war's end. RELATED: Diablo 3: Every Class, Ranked Worst To Best According to The Realms Beyond (as found in the first game in the series), the term 'Sin War' was a term used by Diablo to describe the battle for Sanctuary when conversing with Lazarus. The Sin War was the term used to describe the constant battle Heaven and Hell waged over the dominion of man. In the original Diablo I game the term referred to a much larger timespan, from the first contact between Heaven, Hell and Sanctuary to the present day. Three thousand years before the darkening of Tristram, Uldyssian, son of Diomedes, was a simple farmer from the village of Seram. The concept of the Sin War has undergone major changes in the lore over the years. Moreover, Lilith would come to learn of such alterations and form a plan of her own. This is the tale of the Sin War- the conflict that would forever change the destiny of man.

However, despite these machinations, time would have its way of revealing the realm to the warring sides of the High Heavens and the Burning Hells.

This alteration would cause the formation of powerless Humans, as well as the hiding of Sanctuary's true nature. After Lilith's banishment, Inarius altered the Worldstone to ensure the Nephalem would produce weaker offsprings throughout the generations.

Diablo the sin war