We can trade quotes back and forth all night, both of Adams speaking for and against religion. Quite simply, like most politicians, he used religion as a means of getting elected.
More fuel to the fire:
P.S. I'm exceeding drunk at the moment, so forgive me if I don't actually make any valid arguments relating to the OP.
As I understand the Christian religion, it was, and is, a revelation. But how has it happened that millions of fables, tales, legends, have been blended with both Jewish and Christian revelation that have made them the most bloody religion that ever existed?
-- John Adams, letter to F.A. Van der Kamp, December 27, 1816
When philosophic reason is clear and certain by intuition or necessary induction, no subsequent revelation supported by prophecies or miracles can supersede it.
-- John Adams, from Rufus K. Noyes, Views of Religion
Indeed, Mr. Jefferson, what could be invented to debase the ancient Christianism which Greeks, Romans, Hebrews and Christian factions, above all the Catholics, have not fraudulently imposed upon the public? Miracles after miracles have rolled down in torrents.
-- John Adams, letter to Thomas Jefferson, December 3, 1813
Let the human mind loose. It must be loose. It will be loose. Superstition and dogmatism cannot confine it.
-- John Adams, letter to his son, John Quincy Adams, November 13, 1816
Lisa, if the Bible has taught us nothing else -- and it hasn't -- it's that girls should stick to girl's sports, such as hot oil wrestling and foxy boxing and such and such.
-- Homer Simpson
You know, the one with all the well-meaning rules that don't work in real life -- uh, Christianity.
-- Homer Simpson, telling what religion the family belongs to
I almost shudder at the thought of alluding to the most fatal example of the abuses of grief which the history of mankind has preserved -- the Cross. Consider what calamities that engine of grief has produced!
-- John Adams, letter to Thomas Jefferson, from George Seldes
The priesthood have, in all ancient nations, nearly monopolized learning.... And, even since the Reformation, when or where has existed a Protestant or dissenting sect who would tolerate A FREE INQUIRY? The blackest billingsgate, the most ungentlemanly insolence, the most yahooish brutality is patiently endured, countenanced, propagated, and applauded. But touch a solemn truth in collision with a dogma of a sect, though capable of the clearest proof, and you will soon find you have disturbed a nest, and the hornets will swarm about your legs and hands, and fly into your face and eyes.
-- John Adams, letter to John Taylor, 1814, quoted in Norman Cousins, In God We Trust: The Religious Beliefs and Ideas of the American Founding Fathers (1958)
The Church of Rome has made it an article of faith that no man can be saved out of their church, and all other religious sects approach this dreadful opinion in proportion to their ignorance, and the influence of ignorant or wicked priests.
-- John Adams, Diary and Autobiography
What havoc has been made of books through every century of the Christian era? Where are fifty gospels condemned as spurious by the bull of Pope Gelasius? Where are forty wagon-loads of Hebrew manuscripts burned in France, by order of another pope, because of suspected heresy? Remember the Index Expurgato-rius, the Inquisition, the stake, the axe, the halter, and the guillotine; and, oh! horrible, the rack! This is as bad, if not worse, than a slow fire. Nor should the Lion's Mouth be forgotten. Have you considered that system of holy lies and pious frauds that has raged and triumphed for 1,500 years.
-- John Adams, letter to John Taylor, 1814, quoted by Norman Cousins in In God We Trust: The Religious Beliefs and Ideas of the American Founding Fathers
God is an essence that we know nothing of. Until this awful blasphemy is got rid of, there never will be any liberal science in the world.
-- John Adams, "this awful blashpemy" that he refers to is the myth of the Incarnation of Christ, from Ira D. Cardiff, What Great Men Think of Religion
We think ourselves possessed, or, at least, we boast that we are so, of liberty of conscience on all subjects, and of the right of free inquiry and private judgment in all cases, and yet how far are we from these exalted privileges in fact! There exists, I believe, throughout the whole Christian world, a law which makes it blasphemy to deny or doubt the divine inspiration of all the books of the Old and New Testaments, from Genesis to Revelations. In most countries of Europe it is punished by fire at the stake, or the rack, or the wheel. In England itself it is punished by boring through the tongue with a red-hot poker. In America it is not better; even in our own Massachusetts, which I believe, upon the whole, is as temperate and moderate in religious zeal as most of the States, a law was made in the latter end of the last century, repealing the cruel punishments of the former laws, but substituting fine and imprisonment upon all those blasphemers upon any book of the Old Testament or New. Now, what free inquiry, when a writer must surely encounter the risk of fine or imprisonment for adducing any argument for investigating into the divine authority of those books? Who would run the risk of translating Dupuis? But I cannot enlarge upon this subject, though I have it much at heart. I think such laws a great embarrassment, great obstructions to the improvement of the human mind. Books that cannot bear examination, certainly ought not to be established as divine inspiration by penal laws. It is true, few persons appear desirous to put such laws in execution, and it is also true that some few persons are hardy enough to venture to depart from them. But as long as they continue in force as laws, the human mind must make an awkward and clumsy progress in its investigations. I wish they were repealed. The substance and essence of Christianity, as I understand it, is eternal and unchangeable, and will bear examination forever, but it has been mixed with extraneous ingredients, which I think will not bear examination, and they ought to be separated. Adieu.
-- John Adams, one of his last letters to Thomas Jefferson, January 23, 1825
Numberless have been the systems of iniquity The most refined, sublime, extensive, and astonishing constitution of policy that ever was conceived by the mind of man was framed by the Romish clergy for the aggrandizement of their own Order They even persuaded mankind to believe, faithfully and undoubtingly, that God Almighty had entrusted them with the keys of heaven, whose gates they might open and close at pleasure ... with authority to license all sorts of sins and Crimes ... or withholding the rain of heaven and the beams of the sun; with the management of earthquakes, pestilence, and famine; nay, with the mysterious, awful, incomprehensible power of creating out of bread and wine the flesh and blood of God himself. All these opinions they were enabled to spread and rivet among the people by reducing their minds to a state of sordid ignorance and staring timidity, and by infusing into them a religious horror of letters and knowledge. Thus was human nature chained fast for ages in a cruel, shameful, and deplorable servitude....
Of all the nonsense and delusion which had ever passed through the mind of man, none had ever been more extravagant than the notions of absolutions, indelible characters, uninterrupted successions, and the rest of those fantastical ideas, derived from the canon law, which had thrown such a glare of mystery, sanctity, reverence, and right reverend eminence and holiness around the idea of a priest as no mortal could deserve ... the ridiculous fancies of sanctified effluvia from episcopal fingers.
-- John Adams, "A Dissertation on the Canon and the Feudal Law," printed in the Boston Gazette, August 1765