The letter, penned in Germen in 1954 by the acclaimed physicist to philosopher Eric Gutkind, is commonly referred to as the "God letter".
The Jewish Nobel Prize-winning scientist wrote: "The word God is for me is nothing more than the expression and product of human weaknesses, the Bible a collection of honorable, but still primitive legends which are nevertheless pretty childish.
"No interpretation, no matter how subtle, can (for me) change this."
Einstein wrote to Gutkind after reading his book Choose Life: The Biblical Call to Revolt.
"For me the Jewish religion like all other religions is an incarnation of the most childish superstition," Einstein continued in his letter.
"And the Jewish people to whom I gladly belong, and whose thinking I have a deep affinity for, have no different quality for me than all other people.
"As far as my experience goes, they are also no better than other human groups, although they are protected from the worst cancers by a lack of power. Otherwise I cannot see anything 'chosen' about them."
The auction house estimates it could be sold for at least $1 million.
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