“I am bold to Say that neither you nor I, will live to See the Course which 'the Wonders of the Times' will take. Many Years, and perhaps Centuries must pass, before the current will acquire a Settled direction... yet Platonic, Pythagoric, Hindoo, and cabalistic Christianity, which is Catholic Christianity, and which has prevailed for 1,500 years, has received a mortal wound, of which the monster must finally die. Yet so strong is his constitution, that he may endure for centuries before he expires.{Letter to Thomas Jefferson, July 16 1814}”

“Can a free government possibly exist with the Roman Catholic religion?{Letter to Thomas Jefferson, May 19, 1821}”

“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! With the rational respect that is due to it, knavish priests have added prostitutions of it, that fill or might fill the blackest and bloodiest pages of human history.{Letter to Thomas Jefferson, September 3, 1816]”

“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 to 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 much better; even in our 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 blasphemies 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 arguments for investigation into the divine authority of those books? Who would run the risk of translating Volney's Recherches Nouvelles? 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... 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.{Letter to Thomas Jefferson, January 23, 1825}”

“Many years later, another Marxian rephrased this as the choice between socialism and barbarity. Which of these will prevail is a question which the twenty-first century must be left to answer.”

“Human nature with all its infirmities and deprivation is still capable of great things. It is capable of attaining to degrees of wisdom and goodness, which we have reason to believe, appear as respectable in the estimation of superior intelligences. Education makes a greater difference between man and man, than nature has made between man and brute. The virtues and powers to which men may be trained, by early education and constant discipline, are truly sublime and astonishing. Isaac Newton and John Locke are examples of the deep sagacity which may be acquired by long habits of thinking and study.”

“...Turn our thoughts, in the next place, to the characters of learned men. The priesthood have, in all ancient nations, nearly monopolized learning. Read over again all the accounts we have of Hindoos, Chaldeans, Persians, Greeks, Romans, Celts, Teutons, we shall find that priests had all the knowledge, and really governed all mankind. Examine Mahometanism, trace Christianity from its first promulgation; knowledge has been almost exclusively confined to the clergy. 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.[Letters to John Taylor, 1814, XVIII, p. 484]”