Answer: He used his own mathematical reasoning rather than the Church‘s teachings
Explanation: Isaac Newton, although religious, believed that all phenomena in nature could be explained by scientific principles and theories, because natural laws prevail in nature. This is in direct contradiction to the Church teaching, which explained the same phenomena by the will of God, and the explanations of these phenomena were to be acquired by faith, not by scientific evidence. Thus, with his Mathematical Principles of Natural Philosophy, Newton supported secularism and the thesis that everything in nature could be explained by science, because the same nature was entrusted to humans for preservation, study and use. This does not mean neglecting God, but the thesis that humans are free to use, study, and manage the world God created for their own sake. Thus, he explained with his mathematical principles and laws of motion many phenomena in nature, such as gravity, then the movement of celestial bodies, etc. So the scientific study of nature and the universe, discovering the causes of these phenomena directly encourage secularism.