You frequently state, and in your letter you imply, that I have developed a completely one-sided outlook and look at everything in terms of science. Obviously my method of thought and reasoning is influenced by a scientific training – if that were not so my scientific training will have been a waste and a failure. But you look at science (or at least talk of it) as some sort of demoralizing invention of man, something apart from real life, and which must be cautiously guarded and kept separate from everyday existence. But science and everyday life cannot and should not be separated. Science, for me, gives a partial explanation of life. In so far as it goes, it is based on fact, experience and experiment. Your theories are those which you and many other people find easiest and pleasantest to believe, but so far as I can see, they have no foundation other than they leaf to a pleasanter view of life (and an exaggerated idea of our own importance)...I agree that faith is essential to success in life (success of any sort) but I do not accept your definition of faith, i.e. belief in life after death. In my view, all that is necessary for faith is the belief that by doing our best we shall come nearer to success and that success in our aims (the improvement of the lot of mankind, present and future) is worth attaining. Anyone able to believe in all that religion implies obviously must have such faith, but I maintain that faith in this world is perfectly possible without faith in another world…It has just occurred to me that you may raise the question of the creator. A creator of what? ... I see no reason to believe that a creator of protoplasm or primeval matter, if such there be, has any reason to be interested in our significant race in a tiny corner of the universe, and still less in us, as still more significant individuals. Again, I see no reason why the belief that we are insignificant or fortuitous should lessen our faith – as I have defined it.
...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.
...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.