The Christians say it's the spirit of evil, but this is due to a lack of understanding.

Theon always told me that the true interpretation of the Biblical story of the serpent in the Garden of Eden is that humanity wanted to pass from a state of animal-like divinity to the state of conscious divinity by means of mental development, symbolized by eating the fruit of the Tree of Knowledge. And this serpent, which Theon always said was iridescent, reflecting all the colors of the prism, was not at all the spirit of evil, but the power of evolution - the force, the power of evolution. And it was natural that this power of evolution would make them taste the fruit of knowledge.

Now, according to Theon, Jehovah was the chief of the Asuras, [[Asura: demon of the mental plane embodying the forces of division and darkness. ]] the supreme Asura, the egoistic God who wanted to dominate everything and keep everything under his control. And of course this act made him furious, for it enabled mankind to become gods through the power of an evolution of consciousness. And that's why he banished them from Paradise.

Although told in a childish manner, there's a great deal of truth in this story, a great deal.

page 62 , Mother's Agenda , volume 2 , 4th Feb. - 1961