For Jefferson, an Enlightenment rationalist, reason had to govern in all areas, including religion. “For the use of … reason… every one is responsible to the God who has planted it in his breast, as a light for his guidance, and that, by which alone he will be judged,” Jefferson explained.
2 His declaration to Benjamin Rush that “I have sworn upon the altar of god eternal hostility against every form of tyranny over the mind of man,” was made in the context of religious freedom: any government effort to control religious beliefs was “tyranny over the mind of man.”