As deism is not organized, its adherents differ widely in important matters of belief, but all are in agreement in denying the significance of revelation in Christian Scripture and Tradition.
Deists argue against Catholicism by either, only considering Scripture to be a helpful moral tool, or denying: its divine character, the infallibility of the Church and Traditions, and the validity of its evidence as a complete manifestation of the will of God.
[1] A Deist is defined as "One who believes in the existence of a God or Supreme Being but denies revealed religion, basing his belief on the light of nature and reason.
Because of the individualistic standpoint which they adopt, it is difficult to class together the representative writers who contributed to the literature of English deism as forming any one definite school, or to group together the positive teachings contained in their writings as any one systematic expression of a concordant philosophy.
Others rested content with a criticism of ecclesiastical authority in teaching the inspiration of the Sacred Scriptures, or the fact of an external revelation of supernatural truth given by God to man.
Betts argues that the accounts of Deists at Lyon (France) suggest that the origin of the term Deism lies in the anti-Trinitarian movement which was then an important phenomenon in the religious life of Europe.
The new life of the empirical sciences, the enormous enlargement of the physical horizon in such discoveries as those of astronomy and geography, the philosophical doubt and rationalistic method of Descartes, the advocated empiricism of Bacon, the political changes of the times--all these things were factors in the preparation and arrangement of a stage upon which a criticism levelled at revelational religion might come forward and play its part.
And though the first essays of deism were somewhat veiled and intentionally indirect in their attack upon revelation, with the revolution and the civil and religious liberty consequent upon it, with the spread of the critical and empirical spirit as exemplified in the philosophy of Locke, the time was ripe for the full rehearsal of the case against Christianity as expounded by the Establishment and the sects.
His attempt to ground theological beliefs on reason encountered intense opposition in his time, however: Pascal regarded Descartes's views as rationalist and mechanist, and accused him of deism.
[12] Later on, Cartesian dualism reinforced natural theology in 18th century French deism, especially in the writings of Claude Gilbert and in the anonymous Militaire philosophe.
[13] In 1824 Pope Leo XII issued Ubi Primum discussing a number of concerns, from bishops residing in their dioceses to the popularity of indifferentism, which he also associated with deism.