How is Dark Messiah connected to Heroes of Might and Magic?

If everyone shared the same faith... Orcs believe in Father Sky and Mother Earth, necromancers in Arachne, demons in Urgash, humans in Erathia, high elves in Silanna, dark elves in Malassa, dwarves in Arkat, and mages have no faith at all. That's why they all separated. The peoples forgot Arachne, replacing her with her servants. Before leaving, she created all of the aforementioned beings to protect each people. There is also the dragon Silat, but few worship him.