 The sun and the crescent moon aligned with each other (in the  opening shot) was a symbol of Zoroastrianism, an ancient Persian  religion that predated Buddhism and Christianity and was based on  the teachings of the prophet Zoroaster (also known as Zarathustra).  This particular alignment symbolized the eternal struggle between  light and darkness. Appropriately enough, the famous "2001 Theme" is  from "Also Sprach Zarathustra" (Thus Spake Zarathustra), the  symphonic poem by Richard Strauss, based on a book by Friedrich  Nietzsche, which contained his famous declaration "God is dead". One  can assume, given Kubricks working methods, that none of this was  accidental.