Charles Krauthammer claims:
"Newton's religion was traditional. He was a staunch believer in Christianity and a member of the Church of England."
Actually, economist John Maynard Keynes's 1936 purchase of a trove of Newton's private papers at an auction opened the door to Newton's mystical side, which was unorthodox in the extreme. Newton spent an enormous amount of the first half of his life engaged in "Bible Code"-style attempts to discover the secrets of the universe by deciphering the secrets God had embedded in ancient sacred writings.
Keynes wrote that Newton "was the last of the magicians... His deepest instincts were occult, esoteric, semantic... Very early in life Newton abandoned orthodox belief in the Trinity... He was rather a Judaic monotheist of the school of Maimonides."
Perhaps fancifully, I rather suspect that Newton saw Jesus Christ, with whom he shared December 25th as a birthday, less as his Savior than as his rival.
After the publication of his Principia when he was 45, Newton's friends tried to get him out of his solitary life before he went completely around the bend. He had a nervous breakdown a few years later and when he had recovered, he had apparently lost his unique powers of mind, but still had plenty of mental horsepower left to function as a high level civil servant running the mint. He lived on for decades, becoming a tourist attraction for visitors to England like Voltaire as a benign emblem of the Age of Reason. After his death the true nature of his trunk of private papers, with their anti-Christian and anti-Reason heresies, were covered up for 200 years until Keynes wrote his analysis of what he had found for the celebration of the 300th anniversary of Newton's birth in 1942.