Why was Newton a theist?

[Jehanne]

Isaac Newton, who practically invented physics and calculus, is easily one of the most intelligent people to have ever lived. But he was also a theologian and spent decades studying the bible, theology and church history. Why didn't he use his rationality to denounce Christianity and become an atheist? He lived before Darwin; is this sufficient to excuse his belief in the Christian god?

Newton also had some fantasies of burning his mother alive in her bed:

http://mentalfloss.com/article/24520/6-t...aac-newton

I think that he would have been shocked at the thought of women wearing pants, but having said that, he refused the Anglican sacraments on his deathbed:

https://www.quora.com/Why-did-Isaac-Newt...-his-death

By the way, being an atheist in the early 17th century could be deadly:

https://en.wikipedia.org/wiki/History_of...eformation