In the note, written the year before his death, Einstein dismissed the idea of God as the product of human weakness and the Bible as "pretty childish."
The letter, handwritten in German, is being sold by Bloomsbury Auctions on Thursday and is expected to fetch between $12,000 and $16,000.
In it, Einstein said that "the word God is for me 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."
"For me," he added, "the Jewish religion like all other religions is an incarnation of the most childish superstitions."
Addressing the idea that the Jews are God's chosen people, Einstein wrote that "the Jewish people to whom I gladly belong and with whose mentality I have a deep affinity 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"