The Psychology of Belief

[...]Of course I know that the sort of intellectual arguments that I have been talking to you about is not really what moves people. What really moves people to believe in God is not any intellectual argument at all. Most people believe in God because they have been taught from early infancy to do it, and that is the main reason.

Then I think that the next most powerful reason is the wish for safety, a sort of feeling that there is a big brother who will look after you. That plays a very profound part in influencing people's desire for a belief in God.

[...]As I said before, I do not think that the real reason that people accept religion has anything to do with argumentation. They accept religion on emotional grounds. One is often told that it is a very wrong thing to attack religion, because religion makes men virtuous. So I am told; I have not noticed it.

[...]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 of 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 ever 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.

Religion is based, I think, primarily and mainly upon fear. It is partly the terror of the unknown and partly, as I have said, the wish to feel that you have a kind of elder brother who will stand by you in all your troubles and disputes. Fear is the basis of the whole thing -- fear of the mysterious, fear of defeat, fear of death. Fear is the parent of cruelty, and therefore it is no wonder if cruelty and religion have gone handin-hand. It is because fear is at the basis of those two things.

[Source: Bertrand Russell - Why I Am Not a Christian]