You bring up C.S Lewis, well alright I'll bring up some other names
Gore Vidal: "I'm a born-again atheist."
Mark Twain: "It (the Bible) is full of interest. It has noble poetry in it; and some clever fables; and some blood-drenched history; and some good morals; and a wealth of obscenity; and upwards of a thousand lies." "Faith is believing something you know ain't true."
Thomas Jefferson: "Religions are all alike – founded upon fables and mythologies."
Sigmund Freud: "Religion is comparable to a childhood neurosis."
Lucius Annaeus Seneca: "Religion is regarded by the common people as true, by the wise as false, and by rulers as useful."
John Adams: "This would be the best of all possible worlds, if there were no religion in it."
James Madison: "During almost fifteen centuries has the legal establishment of Christianity been on trial. What has been its fruits? More or less, in all places, pride and indolence in the clergy; ignorance and servility in the laity; in both, superstition, bigotry, and persecution."
Gene Roddenberry: "We must question the story logic of having an all-knowing all-powerful God, who creates faulty Humans, and then blames them for his own mistakes."
George Carlin: "Religion is just mind control."
Benjamin Franklin: "I have found Christian dogma unintelligible. Early in life, I absenteed myself from Christian assemblies." "Lighthouses are more helpful then churches."
Arthur C. Clarke: "Religion is a byproduct of fear. For much of human history, it may have been a necessary evil, but why was it more evil than necessary? Isn't killing people in the name of God a pretty good definition of insanity?"
Albert Einstein: "I cannot imagine a God who rewards and punishes the objects of his creation, whose purposes are modeled after our own -- a God, in short, who is but a reflection of human frailty. Neither can I believe that the individual survives the death of his body, although feeble souls harbor such thoughts through fear or ridiculous egotism."
Ferdinand Magellan: "The church says the earth is flat, but I know that it is round, for I have seen the shadow on the moon, and I have more faith in a shadow than in the church."
Friedrich Wilhelm Nietzsche: "I cannot believe in a God who wants to be praised all the time."
Carl Sagan: "The idea that God is an oversized white male with a flowing beard who sits in the sky and tallies the fall of every sparrow is ludicrous. But if by 'God' one means the set of physical laws that govern the universe, then clearly there is such a God. This God is emotionally unsatisfying... it does not make much sense to pray to the law of gravity.
Stephen F Roberts: "I contend we are both atheists, I just believe in one fewer god than you do. When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours."
Susan B. Anthony: "I distrust those people who know so well what God wants them to do because I notice it always coincides with their own desires."
Epicurus: "Is God willing to prevent evil, but not able? Then he is not omnipotent.
Is he able, but not willing? Then he is malevolent.
Is he both able and willing? Then whence cometh evil?
Is he neither able nor willing? Then why call him God?"
Blaise Pascal: "Men never commit evil so fully and joyfuly as when they do it for religious convictions"
Chapman Cohen: "Gods are fragile things; they may be killed by a whiff of science or a dose of common sense."
Voltaire: "Of all religions the Christian is without doubt the one which should inspire tolerance most, although up to now the Christians have been the most intolerant of all men."
Robert G. Ingersoll: "Why should I allow that same God to tell me how to raise my kids, who had to drown His own?"
Denis Diderot: "The philosopher has never killed any priests, whereas the priest has killed a great many philosophers."
Al-Ma'arri: "The world holds two classes of men - intelligent men without religion, and religious men without intelligence."