A 1954 letter in which Albert Einstein expressed his frank and critical thoughts on religion is once again going on the auction block ― and experts bet it could be sold for up to $1.5 million.

The letter, Einstein’s blunt review of a contemporary Jewish philosopher’s book, offers insight into what the renowned physicist thought about God and his childhood faith as he approached the end of his life.

“The word God is for me nothing more than the expression and product of human weaknesses, the Bible a collection of honourable, but still primitive legends which are nevertheless pretty childish,” Einstein wrote in German, according to a translation by The Guardian.

© Courtesy of Christies A photograph of

The document, which is now known as “The God Letter,” is scheduled to be sold at Christie’s auction house in New York in early December.

Einstein was born into a secular Jewish family and stepped away from the dogma and doctrine of organised religion over time. His beliefs expanded into what he called a “cosmic religion” ― a way of approaching the universe and all its vast mysteries with an overwhelming sense of awe and a humble awareness of the limitations of the human mind.

By 1954, one year before his death, he had completely rejected the idea of God and the beliefs of his childhood faith.

Einstein expressed his views in a candid private letter to the Jewish philosopher Eric Gutkind, who had sent a copy of his book about intellectualism and Jewish spirituality, Choose Life: The Biblical Call to Revolt, to the physicist.

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Einstein wrote that while he had a deep admiration and love for the Jewish people, he had a much harder time accepting the Jewish faith.

“For me the Jewish religion like all other religions is an incarnation of the most childish superstitions,” he wrote. “And 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.”

Einstein tried to avoid religious labels as an adult. He rejected the idea of a “personal God,” claiming that he couldn’t imagine a God who “rewards and punishes the objects of his creation, or who has a will of the kind we experience in ourselves.”

At the same time, he roundly dismissed the notion that he was an atheist.

© Sanford Roth via Getty Images Einstein, who was born into a secular Jewish family, came to embrace what he called a “cosmic religion” ― a way of approaching the universe with an overwhelming sense of awe and a humble awareness of the limitations of the human mind.

“You may call me an agnostic, but I do not share the crusading spirit of the professional atheist,” he wrote in a different letter in the 1940s. “I prefer an attitude of humility corresponding to the weakness of our intellectual understanding of nature and of our own being.”

Einstein outlined his idea of a “cosmic religiosity” in a 1954 essay that aired on Edward R. Murrow’s “This I Believe” radio series.

The most beautiful thing we can experience is the Mysterious — the knowledge of the existence of something unfathomable to us, the manifestation of the most profound reason coupled with the most brilliant beauty. ... I am satisfied with the mystery of life’s eternity and with the awareness of — and glimpse into — the marvelous construction of the existing world together with the steadfast determination to comprehend a portion, be it ever so tiny, of the reason that manifests itself in nature. This is the basics of cosmic religiosity, and it appears to me that the most important function of art and science is to awaken this feeling among the receptive and keep it alive.

Einstein’s letter to Gutkind emerged in 2008 and was sold to an anonymous buyer at an auction in London for $404,000, according to The Associated Press.

The letter will be on public view in Palo Alto, California, on Oct. 25 and in New York City from Nov. 1 to Dec. 4.

In 2002, Christie’s sold a letter Einstein wrote to President Franklin Delano Roosevelt for $2,096,000.

Gallery: Albert Einstein in popular culture (Photo Services)