Darren Staloff, Professor of History at the City College of New York and the Graduate Center of the City University of New York, wrote a very helpful article on Deism for the National Humanities Center. In particular he informs how not all forms of Deism were what we think of as "strict Deism" but rather presented themselves as rationalistic forms of Christianity.
Most English deists downplayed the tensions between their rational theology and that of traditional Christianity. Anthony Collins clamed that “freethinking” in religion was not only a natural right but also a biblically enjoined duty. Matthew Tindal, the author of Christianity as Old as the Creation (1730)—the “Bible of Deism”—argued that the religion of nature was recapitulated in Christianity, and the purpose of the Christian revelation was to free men from superstition. Tindal insisted that he was a Christian deist, as did Thomas Chubb who revered Christ as a divine moral teacher but held that reason, not faith, was the final arbiter of religious belief. How seriously to take these claims has been a matter of intense and prolonged debate. Deism was proscribed by law after all; the Toleration Act of 1689 had specifically excluded all forms of anti-trinitarianism as well as Catholicism. Even in an age of increasing toleration, flaunting one’s heterodoxy could be a dangerous affair, driving many authors into esotericism if not outright deception. When Thomas Woolston attacked the scriptural accounts of miracles and the doctrine of the resurrection, he was fined one hundred pounds sterling and sentenced to one year in prison. Certainly, some deists adopted a materialistic determinism that smacked of atheism. Others, like Collins, Bolingbroke, and Chubb, questioned the immortality of the soul. Even more challenging was the propensity to ascribe the supernatural elements of the Christian religion to “priestcraft,” the cunning deceptions of clergymen who gulled their ignorant flocks by throwing the pixie dust of “mystery” in their eyes. The Dudleian lecture, endowed by Paul Dudley in 1750, is the oldest endowed lecture at Harvard University. Dudley specified that the lecture should be given once a year, and that the topics of the lectures should rotate among four themes: natural religion, revealed religion, the Romish church, and the validity of the ordination of ministers. The first lecture was given in 1755, and it continues to the present day.On the other hand, the rational theology of the deists had been an intrinsic part of Christian thought since Thomas Aquinas, and the argument from design was trumpeted from Anglophone Protestant pulpits of most denominations on both sides of the Atlantic. In fact, Harvard instituted a regular series of lectures on natural religion in 1755. Even anti-clericalism had a fine pedigree among dissenting English Protestants since the Reformation. And it is not inconceivable that many deists might have seen themselves as the culmination of the Reformation process, practicing the priesthood of all believers by subjecting all authority, even that of scripture, to the faculty of reason that God had given humanity.