(CNN) A letter penned by Albert Einstein in which he challenges the concept of religion has broken sale records at auction, fetching close to $2.9 million.

Einstein's "God letter," which he sent to religious philosopher Erik Gutkind, was expected to fetch between $1 million and $1.5 million at Christie's in New York.

The letter instead reached a grand total of $2,892,500 on Tuesday following a four-minute bidding battle between two clients on the phones, setting a world auction record for an Einstein letter.

The letter was sold alongside other fine printed books and manuscripts, including Charles Darwin's "On the Origin of Species by Means of Natural Selection," which achieved $162,500. In total, the auction drew a combined sum of $8,318,125.

The letter was expected to fetch between $1 million and $1.5 million.

"Collectors worldwide competed very strongly, in the room, over the phone and online, for this finely curated auction which comprised masterpieces and fresh-to-market property across a wide range of subjects," said Sven Becker, head of books and manuscripts at Christie's.

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