Newton's research on ancient religious history was very distinctive. He believed all nations were descendants of Noah, and their religions came from Noah's age, too, therefore gods of all nations came from the same origin. Newton expressed his ideal of the pure religion in his research on religious history, he believed all kinds of religions were simple and pure in their early ages, while added with the corrupted doctrines and doctrines in later ages. Newton's research on the religious history indicated two contradictory characteristics, on the one hand, it reveals the inclination of "euhemerism," which means he thought of the ancient mythologies, especially the Bible, as the credible realities. While, on the other hand, he attached much importance to the empirical historical materials, which often made him doubt on the Bible unconsciously. This kind of tension in Newton's idea of theology can be understood better by surveying of the general knowledge and faith in that times.