Existentialism isn't so atheistic that it wears itself out showing that God doesn't exist. Rather, it declares that even if God did exist, that would change nothing.
Hast thou reason? I have.
Why then dost not thou use it?
For if this does its own work,
what else dost thou wish?
Our ignorance is God; what we know is science.
Robert G. Ingersoll
The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one. The happiness of credulity is a cheap and dangerous quality.
George Bernard Shaw
To sum up:
1. The cosmos is a gigantic flywheel making 10,000 revolutions a minute.
2. Man is a sick fly taking a dizzy ride on it.
3. Religion is the theory that the wheel was designed and set spinning to give him a ride.
H. L. Mencken
I do not believe in the creed professed by the Jewish Church, by the Roman Church, by the Greek Church, by the Turkish (Muslim) Church, by the Protestant Church, nor by any Church that I know of. My own mind is my own Church.
Suppose we've chosen the wrong god. Every time we go to church we're just making him madder and madder.
Scientific research confirms that humans are a link in the evolutionary life chain. There is no credible evidence for the existence of an immortal supernatural element. Our only life is here and now. Make it worthy of a moral person.
Keith S. Cornish
Religion is fundamentally opposed to everything I hold in veneration - courage, clear thinking, honesty, fairness, and, above all, love of the truth.
H. L. Mencken
I cannot be angry at God, in whom I do not believe.