Human Nature, the Transcendent, and Truth (and the Seasonal Tolerance for Untruth)

I believe that humans are hard-wired to believe in a reality beyond the material world, and that this belief is most clearly evident in children.  So when we facilitate our children's belief in Santa (or the tooth fairy), are we supporting a healthy exercise of their capacity to believe in the unseen, or are we unhealthily fostering confusion between reality and make-believe?  In my house, we try to proceed carefully, not dispelling our daughters' belief prematurely but also not propping it up after they begin to show skepticism.  Last night my 6 year-old was quizzing me about the tooth fairy (she has been a frequent visitor lately), then related that one of her classmates told her that "Jesus and God aren't real -- they were just made up by some guy."  (In first grade!)  At that moment, my instinct was to pull back the curtain on Santa and the tooth fairy, then have a long talk about the historical reliability of the New Testament documents.  Thankfully, I remembered not to drop my own baggage on my 6 year-old, so I gently affirmed the reality of God and Jesus but did not attempt to disprove her other objects of faith.

But my question remains: do we strengthen or diminish our children's inclination toward faith when we prop up society's portrayal of make-believe as reality?  Our society is more than willing to lump Jesus in with Santa and the tooth fairy, and if we want to avoid that categorization, shouldn't we be drawing the boundaries now?