...Whilst on board the Beagle I was quite orthodox, and I remember being heartily laughed at by several of the officers... for quoting the Bible as an unanswerable authority on some point of morality... But I had gradually come by this time, i.e., 1836 to 1839, to see that the Old Testament from its manifestly false history of the world, with the Tower of Babel, the rainbow at sign, &c., &c., and from its attributing to God the feelings of a revengeful tyrant, was no more to be trusted than the sacred books of the Hindoos, or the beliefs of any barbarian....By further reflecting that the clearest evidence would be requisite to make any sane man believe in the miracles by which Christianity is supported, (and that the more we know of the fixed laws of nature the more incredible do miracles become), that the men at that time were ignorant and credulous to a degree almost uncomprehensible by us, that the Gospels cannot be proved to have been written simultaneously with the events, that they differ in many important details, far too important, as it seemed to me, to be admitted as the usual inaccuracies of eyewitnesses; by such reflections as these, which I give not as having the least novelty or value, but as they influenced me, I gradually came to disbelieve in Christianity as a divine revelation. The fact that many false religions have spread over large portions of the earth like wild-fire had some weight with me. Beautiful as is the morality of the New Testament, it can be hardly denied that its perfection depends in part on the interpretation which we now put on metaphors and allegories.But I was very unwilling to give up my belief... Thus disbelief crept over me at a very slow rate, but was at last complete. The rate was so slow that I felt no distress, and have never since doubted even for a single second that my conclusion was correct. I can indeed hardly see how anyone ought to wish Christianity to be true; for if so the plain language of the text seems to show that the men who do not believe, and this would include my Father, Brother and almost all of my friends, will be everlastingly punished. And this is a damnable doctrine.
Study, along the lines which the theologies have mapped, will never lead us to discovery of the fundamental facts of our existence. That goal must be attained by means of exact science and can only be achieved by such means. The fact that man, for ages, has superstitiously believed in what he calls a God does not prove at all that his theory has been right. There have been many gods – all makeshifts, born of inability to fathom the deep fundamental truth. There must be something at the bottom of existence, and man, in ignorance, being unable to discover what it is through reason, because his reason has been so imperfect, undeveloped, has used, instead, imagination, and created figments, of one kind or another, which, according to the country he was born in, the suggestions of his environment, satisfied him for the time being. Not one of all the gods of all the various theologies has ever really been proved. We accept no ordinary scientific fact without the final proof; why should we, then, be satisfied in this most mighty of all matters, with a mere theory?Destruction of false theories will not decrease the sum of human happiness in future, any more than it has in the past... The days of miracles have passed. I do not believe, of course, that there was ever any day of actual miracles. I cannot understand that there were ever any miracles at all. My guide must be my reason, and at thought of miracles my reason is rebellious. Personally, I do not believe that Christ laid claim to doing miracles, or asserted that he had miraculous power...Our intelligence is the aggregate intelligence of the cells which make us up. There is no soul, distinct from mind, and what we speak of as the mind is just the aggregate intelligence of cells. It is fallacious to declare that we have souls apart from animal intelligence, apart from brains. It is the brain that keeps us going. There is nothing beyond that.Life goes on endlessly, but no more in human beings than in other animals, or, for that matter, than in vegetables. Life, collectively, must be immortal, human beings, individually, cannot be, as I see it, for they are not the individuals – they are mere aggregates of cells.There is no supernatural. We are continually learning new things. There are powers within us which have not yet been developed and they will develop. We shall learn things of ourselves, which will be full of wonders, but none of them will be beyond the na