Personally, I think it would be highly inapproriate (do you spell that like this?) to incorporate "real-world" religious themes into game play, especially if it revolves around a religion that is more or less seriously held by one of the game attendees.
In my group I have a real-life theologist and as a DM it makes me a more than a little uncomfortable adressing issues assimilating issues from real-world religious history, because I do greatly respect his commitment to faith (which I lack) and I do not wish to insult his believes - or that of any other game attendee for that matter. As a matter of fact, I try to avoid building analogies such as Baator <--> Hell, Celestia <--> Heaven in my game nowadays.
As for monotheism itself, I have incorporated cultures/races with monotheistic believes alongside the "standard" D&D polytheistic cultures/races. Some of these groups deny the existence of other gods (calling them by a number of other names, just not gods), others venerate an "overgod-like" being who adresses all portfolios for this group and I used to have some (usually evil) groups completely deny the existence of other gods. The latter onese usually had a very warlike way of convincing others.