I'm not in the least bit superstitious. I don't believe in horoscopes and have little use for much of the New Age philosophies.
That said, I don't speak the name of Macbeth in a performance space and have taught our son to do the same. I follow most of the superstitions of the theater, even though I don't truly believe that they will truly do harm.
While writing about Riverwalk's Macbeth today, I think I finally figured out why I do so. It's the tradition and ritual of theater. Traditions and rituals have value because they connect us to each other and give us a shared practice and a sense of history. They remind us of our stories and give us--however small--a piece of commonality.