It's estimated that Newton devoted more time to the study of scripture than to science, and he was generally considered a religious nut at a time when everyone took their religion pretty seriously. Newton treated the Bible like Russell Crowe treated newspaper clippings in A Beautiful Mind, poring over it for hours, looking for hidden codes. Newton also spent quite a bit of his time trying to figure out the exact measurements of the Temple of Solomon, which he modestly claimed would allow him to predict the exact date of the apocalypse.
Because all numbers add up to a wolf eating the sun.
Not all of Newton's scientific beliefs have stood the test of time quite as well as gravity. For instance, he also poured hours and hours of his time into alchemy. In fact, he was so interested in alchemy that it is now believed that alchemy was his main focus, and real science was more of a pastime for him. Unlike mathematics and the laws of physics, Newton wasn't even trying to take alchemy in new and interesting directions, opting instead to pursue theories that had long since been disregarded by people who still believed alchemy was possible. His time as an alchemist was mainly devoted to creating the philosopher's stone, which he believed could transmute other metals into gold and grant human beings immortality.
Apple-induced head injuries are kind of a double-edged sword for scientists.