tecnowraith said:
I want to use all myths from different religions. Not just one or the other.
Disclaimer. I hope that the following is not in violation of the board policy regarding religion. It is not my intention to discuss the belief systems of any faith, but instead to describe concepts related to the question. End Disclaimer.
Christianity, Judaism, and Islam (and in ancient times Zorastrianism) have what we traditionally consider demons and angels, with Islam adding the ginn. Oriental traditions have things that we translate as "demons" that are essentially evil spirits, such as the Japanese Oni or Indonesian Buta. GURPS Spirits can help with players as otherworldly spirits. Angels, on the other hand, are actually a fairly Western concept. Greek thought has good spirits, eudaemons, and bad spirits, cacodaemons, that behave much as demons and angels do in popular literature in the western traditions. Socrates claimed to have a guiding spirit that protected him and aided him, but never controled what he did. Naturally, Roman mythology incorporates these ideas as well. In Norse myth there are quardian spirits of a place called Landvaettir, which might be associated with guardian angels. In Native American myth guardian spirits also appear, often but not always an totemic or ancestrial aspect. In Chinese mytholgy there are the Hounds of Heaven (the Tian-gou) that hunt evil spirits on behalf of Er-lang. Again, not something I would really associate with angels.
Then there is the melding of African and Christian ideas in Vodun, which again might have beings that at times could be called demons and maybe a few with "angelic" qualties, but even less so that mainstream Christianity.
All of which is to say: I doubt you are going to find a single source book that deals with a wide variety of real world religions or mythologies. GURPS might, if you are willing to build from a ton of different sources.
In developing a campaign, the issue is how you define Angels and Demons. The traditional definitions do not really apply across cultures, but you can find "evil" and "good" spirits in almost any time and place. Their behavior and power levels, however, are going to be radiacally different.
Trying to shut off proffesor mode now. Thank you for your patience.