@The Crimson Ace,
"Even if god existed that would make no difference" What would Nietzsche say?
Nietzsche wasn't stupid enough to claim that God doesn't (or does) exist. Such claims can only be meaningfully made about empirical items, as Kant pointed out. Nietzsche was well versed in Kant's philosophy.
Here is a quote from Nietzsche:
God is dead. God remains dead. And we have killed him. How shall we comfort ourselves, the murderers of all murderers? What was holiest and mightiest of all that the world has yet owned has bled to death under our knives: who will wipe this blood off us? What water is there for us to clean ourselves? What festivals of atonement, what sacred games shall we have to invent? Is not the greatness of this deed too great for us? Must we ourselves not become gods simply to appear worthy of it?
—Nietzsche, The Gay Science, Section 125, tr. Walter Kaufmann
As to Sartre's statement you have quoted, not knowing the context in which it was made makes it difficult to interpret. Taken in the context of Kant's philosophy, we might say that because we can never know the answer to such a question, or even if it is a meaningful question, then God's existence or non-existence could make no conceivable difference to human life.
Having said that, whether or not one BELIEVES in the existence of God could make a great difference to their life.