As Hollywood puts it, it is the greatest story every told (sold?). The story attracts followers quickly and the people latch on the the emotional story and are mesmerized by it. The story has been used all over the world hundrereds and thousand of years before the Jesus story of the Christian New Testament was developed. The original story was about describing the stars and the story evolved to be a literal historical story (with Constantine's help).
The human desire for a "Superman" is so great (It's a bird. It's a plane. No, it's Superman...).
Faster than a speeding bullet, more powerful than a locomotive, able to leap tall buildings in a single bound.