If the Pentateuch be true, religious persecution is a duty. The dungeons of the Inquisition were temples, and the clank of every chain upon the limbs of heresy was music in the ear of God. If the Pentateuch was inspired, every heretic should be destroyed; and every man who advocates a fact inconsistent with the sacred book, should be consumed by sword and flame.In the Old Testament no one is told to reason with a heretic, and not one word is said about relying upon argument, upon education, nor upon intellectual development—nothing except simple brute force. Is there to-day a christian who will say that four thousand years ago, it was the duty of a husband to kill his wife if she differed with him upon the subject of religion? Is there one who will now say that, under such circumstances, the wife ought to have been killed? Why should God be so jealous of the wooden idols of the heathen? Could he not compete with Baal? Was he envious of the success of the Egyptian magicians? Was it not possible for him to make such a convincing display of his power as to silence forever the voice of unbelief? Did this God have to resort to force to make converts? Was he so ignorant of the structure of the human mind as to believe all honest doubt a crime? If he wished to do away with the idolatry of the Canaanites, why did he not appear to them? Why did he not give them the tables of the law? Why did he only make known his will to a few wandering savages in the desert of Sinai? Will some theologian have the kindness to answer these questions? Will some minister, who now believes in religious liberty, and eloquently denounces the intolerance of Catholicism, explain these things; will he tell us why he worships an intolerant God? Is a god who will burn a soul forever in another world, better than a christian who burns the body for a few hours in this? Is there no intellectual liberty in heaven? Do the angels all discuss questions on the same side? Are all the investigators in perdition? Will the penitent thief, winged and crowned, laugh at the honest folks in hell? Will the agony of the damned increase or decrease the happiness of God? Will there be, in the universe, an eternal auto da fe?
That is the idea -- that we should all be wicked if we did not hold to the Christian religion. It seems to me that the people who have held to it have been for the most part extremely wicked. You find this curious fact, that the more intense has been the religion of any period and the more profound has been the dogmatic belief, the greater has been the cruelty and the worse has been the state of affairs. In the so-called ages of faith, when men really did believe the Christian religion in all its completeness, there was the Inquisition, with all its tortures; there were millions of unfortunate women burned as witches; and there was every kind of cruelty practiced upon all sorts of people in the name of religion.You find as you look around the world that every single bit of progress in humane feeling, every improvement in the criminal law, every step toward the diminution of war, every step toward better treatment of the colored races, or every mitigation of slavery, every moral progress that there has been in the world, has been consistently opposed by the organized churches of the world. I say quite deliberately that the Christian religion, as organized in its churches, has been and still is the principal enemy of moral progress in the world.You may think that I am going too far when I say that that is still so. I do not think that I am. Take one fact. You will bear with me if I mention it. It is not a pleasant fact, but the churches compel one to mention facts that are not pleasant. Supposing that in this world that we live in today an inexperienced girl is married to a syphilitic man; in that case the Catholic Church says, 'This is an indissoluble sacrament. You must endure celibacy or stay together. And if you stay together, you must not use birth control to prevent the birth of syphilitic children.' Nobody whose natural sympathies have not been warped by dogma, or whose moral nature was not absolutely dead to all sense of suffering, could maintain that it is right and proper that that state of things should continue.That is only an example. There are a great many ways in which, at the present moment, the church, by its insistence upon what it chooses to call morality, inflicts upon all sorts of people undeserved and unnecessary suffering. And of course, as we know, it is in its major part an opponent still of progress and improvement in all the ways that diminish suffering in the world, because it has chosen to label as morality a certain narrow set of rules of conduct which have nothing to do with human happiness; and when you say that this or that ought to be done because it would make for human happiness, they think that has nothing to do with the matter at all. 'What has human happiness to do with morals? The object of morals is not to make people happy.
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.