One of the differences between fantasy and reality shows up when you have lots of people involved. To demonstrate this, I like to use the illustration of Mt. Sinai and the Burning Bush, from the story of Moses.
Suppose you are looking for the summit of Mt. Sinai, high up in the clouds. And let’s say there are several of you, all starting from different places around the base of the mountain. As each of you gets closer to the summit, what happens? You all draw closer to each other as well. Because the summit actually exists in the real world, you all have a common point of reference, and as each one gets closer to the truth, the group as a whole gets closer to each other, until you all finally arrive at the same point. Mt. Sinai illustrates the way scientists gradually converge on the same truth about the real world, by studying a common reality.
The pursuit of fantasy, by contrast, produces quite a different effect. Because the goal you are pursuing does not exist in the real world, there is no common goal towards which all seekers can progress. Fantasy tends to flow along lines drawn by personal bias, cultural influences, political agendas, and other psychological phenomena that push different people in different directions at different times. The result is that pursuing fantasies tends to lead people away from each other, even if they all start from the same point. To the degree that we all share common psychological traits, we may find common branches in our fantasies, with certain types preferring one form, and other types preferring others. But the overall pattern is that of a bush, that branches and re-branches over time as each new seeker adds his or her own unique and subjective perspective.
Thus, the pursuit of truth, when it is really truth, produces a pattern of discovery like Mt. Sinai, where you can start at different places, and draw closer together over time until you all arrive at the same summit. The pursuit of fantasy, as though it were the truth, produces instead the pattern of the Burning Bush, where believers form branches and diverge from one another, even when starting from a common root.
So what is theology? Is it Mt. Sinai, or is it he Burning Bush? The answer will tell us a lot about the truth of the goal being pursued—if we have ears to hear.