As an In Nomine game master, you not only play God, but Lucifer and all the other Superiors . . . Here's the book that will help you do all that, as well as:

This book contains the core rules for the In Nomine roleplaying system. The setting is introduced by two short stories, A Bright Dream and A Dark Dream by author Derek Pearcy. Character creation concepts are discussed, along with the game mechanics, resource mechanics, essense, resonance, dissonance, and falling. In Nomine also describes each of the choirs of angels and bands of demons, introduces 13 Archangels and Demon Princes, and discusses soldiers of God (and Hell), ethereal spirits, celestial spirits, and the undead.