The "gods" of the Realms, also called Powers, are important beings; they grant magical spells to their worshippers, involve themselves in earthly dealings, and grow or diminish in personal power in relation to the number of mortal worshippers they possess.Quite a bit packed into this section's introductory paragraph, isn't there?
Note how the word "gods" is put in quotes there. Right off the bat, we get a picture of gods in the Realms being a lot less, well, god-like than we perhaps associate with that word. They seem to exist much more along the lines of the earliest conceptions of gods, as powerful beings that transcend human abilities and understanding, yet are still very human in their actions and motivations, including frequent meddling in the affairs of mortals.
We also get a note that there is a "plethora of divine beings" in the Realms, and this profusion of divine beings, of whose existence there can be no real doubt, has led to a widespread attitude of tolerance among worshippers. As long as your church's liturgy doesn't call for law-breaking (human sacrifice being particularly frowned upon), you're free to go about your business.
Although this may seem another modernistic contrivance designed to mitigate certain "un-fun" distractions during role-playing, it certainly has many historical precedents. The henotheistic societies of Hellenistic Alexandria, the Roman Empire, or ancient India all spring to mind. This is pretty much bog-standard D&D, and the realm in which D&D and its derived style of fantasy deviates most strongly from "European Middle Ages" model. (And indeed, if I were still doing my Bronze Age Realms mod, this would be the part that would need the least modification. The gods as presented in the Realms are much more Gilgamesh or Herakles than Jehovah or Allah.) Again, I can't help but think of medieval India or China as perhaps more appropriate models than medieval Europe from the perspective of a cultural baseline.
Having gods who take an active interest in the affairs of mortals, who very well may have been mortals at one time, and whose power is very much reliant on how many worshippers they can accrue, has some pretty significant implications for the setting. I'm well aware, of course, of how these implications played out almost immediately after the Gray Box was released, but as I'm limiting my reading to just the contents of the box, it will be interesting to see how it's addressed in the source material, as it were.
Our first indication of these implications at play is the exception noted right here in the text regarding religious tolerance: "Individuals, particularly clerics, may not be all tolerant of the beliefs of others...take care; it is often an affront of the highest order to ask [after which gods a person worships] openly. Some people have been known to attack individuals inquiring as to their faith." This, then, is a world of secret cults, cryptic passwords and handshakes, and sometimes tense sectarian interactions.
Hey, it may not be particularly cod-medieval Europe, but it is pretty cool. What D&D campaign doesn't benefit from some secret cult action?
Next time we'll get into the listing of the "main deities and demigods of the Realms".