“The hocus-pocus phantasm of a God like another Cerberus, with one body and three heads, had its birth and growth in the blood of thousands and thousands of martyrs... In fact, the Athanasian paradox that one is three, and three but one, is so incomprehensible to the human mind, that no candid man can say he has any idea of it, and how can he believe what presents no idea? He who thinks he does, only deceives himself. He proves, also, that man, once surrendering his reason, has no remaining guard against absurdities the most monstrous, and like a ship without a rudder, is the sport of every wind. With such persons, gullibility which they call faith, takes the helm from the hand of reason, and the mind becomes a wreck.[Letter to James Smith discussing Jefferson's hate of the doctrine of the Christian trinity, December 8 1822]”

“Man once surrendering his reason, has no remaining guard against absurdities the most monstrous, and like a ship without rudder, is the sport of every wind. With such persons, gullibility, which they call faith, takes the helm from the hand of reason, and the mind becomes a wreck.”

“Fanaticism is the opposite of love,’ I said, recalling one of Khaderbhai’s lectures. A wise man once told me—he’s a Muslim, by the way—that he has more in common with a rational, reasonable-minded Jew than he does with a fanatic from his own religion. He has more in common with a rational, reasonable-minded Christian or Buddhist or Hindu than he does with a fanatic from his own religion. In fact, he has more in common with a rational, reasonable-minded atheist than he does with a fanatic from his own religion. I agree with him, and I feel the same way. I also agree with Winston Churchill, who once defined a fanatic as someone who won’t change his mind and can’t change the subject.”

“The key to every man is his thought. Sturdy and defying though he look, he has a helm which he obeys, which is the idea after which all his facts are classified. He can only be reformed by showing him a new idea which commands his own.”

“This century will be called Darwin's century. He was one of the greatest men who ever touched this globe. He has explained more of the phenomena of life than all of the religious teachers. Write the name of Charles Darwin on the one hand and the name of every theologian who ever lived on the other, and from that name has come more light to the world than from all of those. His doctrine of evolution, his doctrine of the survival of the fittest, his doctrine of the origin of species, has removed in every thinking mind the last vestige of orthodox Christianity. He has not only stated, but he has demonstrated, that the inspired writer knew nothing of this world, nothing of the origin of man, nothing of geology, nothing of astronomy, nothing of nature; that the Bible is a book written by ignorance--at the instigation of fear. Think of the men who replied to him. Only a few years ago there was no person too ignorant to successfully answer Charles Darwin, and the more ignorant he was the more cheerfully he undertook the task. He was held up to the ridicule, the scorn and contempt of the Christian world, and yet when he died, England was proud to put his dust with that of her noblest and her grandest. Charles Darwin conquered the intellectual world, and his doctrines are now accepted facts. His light has broken in on some of the clergy, and the greatest man who to-day occupies the pulpit of one of the orthodox churches, Henry Ward Beecher, is a believer in the theories of Charles Darwin--a man of more genius than all the clergy of that entire church put together....The church teaches that man was created perfect, and that for six thousand years he has degenerated. Darwin demonstrated the falsity of this dogma. He shows that man has for thousands of ages steadily advanced; that the Garden of Eden is an ignorant myth; that the doctrine of original sin has no foundation in fact; that the atonement is an absurdity; that the serpent did not tempt, and that man did not 'fall.'Charles Darwin destroyed the foundation of orthodox Christianity. There is nothing left but faith in what we know could not and did not happen. Religion and science are enemies. One is a superstition; the other is a fact. One rests upon the false, the other upon the true. One is the result of fear and faith, the other of investigation and reason.”

“To defend something is always to discredit it. Let a man have a warehouse full of gold, let him be willing to give away a ducat to every one of the poor - but let him also be stupid enough to begin this charitable undertaking of his with a defence in which he offers three good reasons in justification; and it will almost come to the point of people finding it doubtful whether indeed he is doing something good. But now for Christianity. Yes, the person who defends that has never believed in it. If he does believe, then the enthusiasm of faith is not a defence, no, it is the assault and the victory; a believer is a victor.”