Religious truth is known by reason, not revelation

Deism affirms that religious truth is known by reason rather than by revelation, that the existence and nature of God, and the basic principles of morality, can be discovered through the exercise of human reason and the observation of nature, without reliance on sacred books, prophets, or churches. Flourishing in the seventeenth and eighteenth centuries, deism held that a rational religion open to all people in all times is more credible than one resting on particular claimed revelations, and it looked to the order of the natural world as evidence of a wise Creator.

Herbert's De Veritate (1624) set out what he called the "five common notions" he held to be inscribed in all human minds independent of any particular revelation: that a supreme deity exists, that this deity ought to be worshipped, that virtuous living is the chief part of worship, that vice and wrongdoing must be repented, and that reward and punishment follow in a life beyond this one. Herbert argued that because these five notions, in his view, recur across cultures and religions that never had contact with one another, they constitute the universal rational core of true religion, with everything beyond them, including the specific scriptures, miracles, and clergy of the particular revealed faiths, an accretion added later by human institutions rather than genuine divine communication.

This affirmation defines deism against the revealed religions, which ground truth in scripture and divine disclosure. The deist accepts a Creator known through reason and nature while setting aside the authority of any particular revelation, and this leads to the further deist positions that miracles and revealed prophecy are not credible and that God does not intervene in the world. As a rational and natural religion, deism influenced Enlightenment thought and several of its leading figures, and it is presented here as the outlook its proponents held.

English deism reached a high point in Matthew Tindal's Christianity as Old as the Creation (1730), often called "the deist's Bible" for its influence, and the outlook spread across Europe and America: Voltaire championed a rational, providential deism against both atheism and revealed Catholic orthodoxy in France, and in the newly independent United States, Thomas Jefferson, working between 1819 and 1820, compiled The Life and Morals of Jesus of Nazareth, now commonly called the Jefferson Bible, by cutting all miracles and supernatural claims from the Gospels while retaining what he considered Jesus's authentic moral teaching, a concrete practical demonstration of deist method applied directly to Christian scripture.