Earlier today, I was thinking about deity and bodhisattva images in Tibetan art (inspired in part by a visit I took a couple of weeks ago to the Rubin Museum, an awesome place I highly recommend to anyone living in or near or visiting NYC), and it got me thinking about the discussion going on here about theism vs. atheism. And I wondered how I would exactly explain these deities and the belief system they represented to someone wanting to know whether Tibetans are "theists" or "atheists." And I found that neither of those labels would suffice to characterize the way these deities are explained and taught about to scholars and "ordinary folk" alike.
The Tibetans have a very complex and refined understanding of mind and reality that offers the most satisfying response I've encountered yet to the questions of "What is reality?" and "What is truth?" (Not that I'm fully satisfied yet, mind you :lol Their basic teaching can be summed up in a classic Buddhist phrase John Daido Loori often uses: "The three worlds are nothing but mind." No matter where you look for reality, you always find your own mind. You can't get away from your own mind. You might be able to base a pretty reasonable opinion or theory on aspects of "reality" that appear to others more or less in the same way as they do to you, but nonetheless there is no way to directly access this knowledge of another person's subjective viewpoint.
The Tibetan understanding of deity acknowledges and incorporates this understanding about the radically subjective nature of our experience of "reality." To the Tibetans, these deities are understood to be, as are all other things, "projections" of the mind. That doesn't mean they're dismissed as "not real" or "figments of the imagination." 'Cause by this view, everything in one's experience is a projection of the mind, including the rock one just stubbed one's toe upon. These deities are perceived to have some sort of "reality," something that can be contacted and communicated with, just not in a necessarily concrete way. To say, for example, "Tara doesn't exist," would be like saying "Love doesn't exist," or "Imagination doesn't exist." One knows that love and imagination exist in some way, yet one cannot point to them in the same way one can point to a "dog" or a "tree."
This also points to the issue of language, and how it shapes our understanding of the world. We don't get in as much trouble with more concrete terms with an obvious referent, because most people who speak the same language can agree as to what is a "dog" or a "car" or a "wheelbarrow." It's when we get into layers of abstraction that we get into trouble. Because we have a word for it, we think we know what we're talking about, but we don't necessarily know that. We may think we know what is meant by the phrase "I believe in God" or the phrase "I don't believe in God," but not only do we by default not know what someone else who utters one of these phrases means by it, we generally don't even know what the hell we mean by it when we say such a thing.