C.E. Joad and Bertrand Russell

C.E. Joad, The Present and Future of Religion, 1930
"To say that there is a God is not to say anything more than that we need to think there is, and the need is in no sense a guarantee of the existence of that which satisfies it. Thus the great religions of the world are not theology, but pyschology; witnesses...to the inventive faculty of man."

Bertrand Russell, Why I am Not a Christian, 1957
"I may say that when I was a young man and was debating these questions very seriously in my mind, I for a long time accepted the argument of the First Cause, until one day, at the age of eighteen, I read John Stuart Mill's Autobiography, and there I found this sentence: 'My father taught me that the question, Who made me? cannot be answered, since it immediately suggests the further question, Who made God?' That very simple sentence showed me, as I still think, the fallacy in the argument of the First Cause. If everything must have a cause, then God must have a cause. If there can be anything without a cause, it may just as well be the world as God, so that there cannot be any validity in that argument. It is exactly of the same nature as the Hindu's view, that the world rested upon an elephant and the elephant rested upon a tortoise; and when they said, 'How about the tortoise?' the Indian said, 'Suppose we change the subject.' The argument is really no better than that. There is no reason why the world could not have come into being without a cause; nor, on the other hand, is there any reason why is should not have always existed. There is no reason to suppose that the world had a beginning at all. The idea that things must have a beginning is really due to the poverty of our imagination."

A bit of Marx

It's a particularly famous quote, but I thought I'd post a bit more of it than is typically mentioned.

“Religious misery is in one mouth the expression of real misery, and in another is a protestation against real misery. Religion is the moan of the oppressed creature, the sentiment of a heartless world, as it is the spirit of spiritless conditions. It is the opium of the people. The abolition of religion, as the illusory happiness of the people, is the demand for their real happiness. The demand to abandon the illusions about their condition is a demand to abandon a condition which requires illusions.” (Marx, A Criticism of the Hegelian Philosophy of Right)