What theological doctrine did Isaac Newton reject?

Isaac Newton rejected the doctrine of the Trinity. Although he was raised Anglican and wrote extensively about Christianity, his private theological views were unorthodox. He rejected the conventional claim that God exists as three coequal persons—Father, Son, and Holy Spirit—and instead regarded Christ as divine but subordinate to the Father.

Newton’s religious writings show a strong interest in early Christian history, biblical prophecy, and the disputes surrounding the formulation of orthodox creeds. His position was influenced by anti-Trinitarian currents associated with figures such as Arius and the later Socinians. Because such views could have damaged his career in the Church of England, Newton kept them private and did not openly declare himself a heretic.

The conclusion was disputed by earlier biographers, who had incomplete access to his papers. In the twentieth century, the deciphering and study of Newton’s theological manuscripts made his rejection of Trinitarianism much clearer. This is why “Trinity” is the canonical quiz answer, rather than broader labels such as Arianism or anti-Trinitarianism.