Reason, the Only Oracle of Man: Or, a Compendious System of Natural Religion

Reason, the Only Oracle of Man is Colonel Ethan Allen's polemical treatise wherein he argues for the power of reason, and reason's nature as a God-given attribute of man.
Received to a negative reception during its original publication in 1785, Reason, the Only Oracle of Man divided opinion on the grounds of its rejection of traditional, Christian religious beliefs. At the time, the fledgling nation of the United States was deeply devoted to the traditional Christian establishment, with many suspicious of the recent progress of science in many fields.
Ethan Allen rejected many traditional beliefs of the Christian church. He considered much of the Bible to be mythical superstition, and held great contempt for organised religion which he viewed as corrupt and sinful, with the priesthood in particular targeted for its inadequacies. While not an atheist, Allen believed strongly in the power and capacity of reason, and considered its use to be virtuous.
Although sales were poor and condemnation for the book was near-universal, it would receive some positive regard in scholarly circles. In absorbing the financial loss the book incurred, Allen wryly observed that most critics of the book were clergymen who depended on established Christianity for their livelihoods.
Despite its failure, Reason would eventually return to print and enjoy modest sales many years after Allen's death. As one of the few public figures at the time of the American Revolutionary War to lambaste religion, Allen remains a figure of some interest to historians for his iconoclasm and convictions of belief.