The following 101 quotes are some that I have stumbled upon on the web, or seen in books / popular culture. Each quote was either written by an atheist, or is about atheism / religion in general.
1. The fact that a believer is happier than a sceptic 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
2. Faith means not wanting to know what is true. - Friedrich Nietzsche
3. I believe in God, only I spell it Nature. - Frank Lloyd Wright
4. 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. - Gene Roddenberry
5. To surrender to ignorance and call it God has always been premature, and it remains premature today. - Isaac Asimov
6. A man is accepted into a church for what he believes and he is turned out for what he knows. - Samuel Clemens (Mark Twain)
7. Religion is regarded by the common people as true, by the wise as false, and by the rulers as useful. - Seneca the Younger
8. Philosophy is questions that may never be answered. Religion is answers that may never be questioned. - Anonymous
9. Not only is there no god, but try getting a plumber on weekends. - Woody Allen
10. If I were not an atheist, I would believe in a God who would choose to save people on the basis of the totality of their lives and not the pattern of their words. I think he would prefer an honest and righteous atheist to a TV preacher whose every word is God, God, God, and whose every deed is foul, foul, foul. - Isaac Asimov
11. Belief in the supernatural reflects a failure of the imagination. - Edward Abbey
12. With or without religion, you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion. - Steven Weinberg
13. I still say a church steeple with a lightning rod on top shows a lack of confidence. - Doug McLeod
14. The world holds two classes of men - intelligent men without religion, and religious men without intelligence. - Abu'l‐Ala al Ma'arri
15. Since the Bible and the church are obviously mistaken in telling us where we came from, how can we trust them to tell us where we are going? - Anonymous
16. I distrust those people who know so well what God wants them to do because I notice it always coincides with their own desires. - Susan B. Anthony
17. The invisible and the non-existent look very much alike. - Delos B. McKown
18. Two hands working can do more than a thousand clasped in prayer. - Anonymous
19. Atheism leaves a man to sense, to philosophy, to natural piety, to laws, to reputation; all of which may be guides to an outward moral virtue, even if religion vanished; but religious superstition dismounts all these and erects an absolute monarchy in the minds of men. - Francis Bacon
20. The God of the Old Testament is arguably the most unpleasant character in all fiction: jealous and proud of it; a petty, unjust, unforgiving control-freak; a vindictive, bloodthirsty ethnic cleanser; a misogynistic, homophobic, racist, infanticidal, genocidal, filicidal, pestilential, megalomaniacal, sadomasochistic, capriciously malevolent bully. - Richard Dawkins
21. A God who kept tinkering with the universe was absurd; a God who interfered with human freedom and creativity was tyrant. If God is seen as a self in a world of his own, an ego that relates to a thought, a cause separate from its effect. he becomes a being, not Being itself. An omnipotent, all‐knowing tyrant is not so different from earthly dictators who make everything and everybody mere cogs in the machine which they controlled. An atheism that rejects such a God is amply justified. - Karen Armstrong
22. It is not as in the Bible, that God created man in his own image. But, on the contrary, man created God in his own image. - Ludwig Feuerbach
23. People ask me what I think about that woman priest thing. What, a woman priest? Women priests. Great, great. Now there's priests of both sexes I don't listen to. - Bill Hicks
24. All the biblical miracles will at last disappear with the progress of science. - Matthew Arnold
25. Blind faith is an ironic gift to return to the Creator of human intelligence. - Anonymous
26. Be thankful that you have a life, and forsake your vain and presumptuous desire for a second one. - Richard Dawkins
27. What can be asserted without proof can be dismissed without proof. - Christopher Hitchens
28. In Christianity neither morality nor religion come into contact with reality at any point. - Friedrich Nietzsche
29. It will yet be the proud boast of women that they never contributed a line to the Bible. - George W. Foote
30. On the first day, man created God. - Anonymous
31. I contend that 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. - Stephen Roberts
32. You do not need the Bible to justify love, but no better tool has been invented to justify hate. - Richard A. Weatherwax
33. What's "God"? Well, you know, when you want something really bad and you close your eyes and you wish for it? God's the guy that ignores you. - Steve Buscemi (From the movie "The Island")
34. As far as I can tell from studying the scriptures, all you do in heaven is pretty much just sit around all day and praise the Lord. I don't know about you, but I think that after the first, oh, I don't know, 50,000,000 years of that I'd start to get a little bored. - Rick Reynolds
35. Give a man a fish and he will eat for a day; teach a man to fish and he will eat for a lifetime; give a man religion and he will die praying for a fish. - Anonymous
36. Calling Atheism a religion is like calling bald a hair color. - Don Hirschberg
37. God should be executed for crimes against humanity. - Bryan Emmanuel Gutierrez
38. To say that atheism requires faith is as dim-witted as saying that disbelief in pixies or leprechauns takes faith. Even if Einstein himself told me there was an elf on my shoulder, I would still ask for proof and I wouldn't be wrong to ask. - Geoff Mather
39. I do not fear death. I had been dead for billions and billions of years before I was born, and had not suffered the slightest inconvenience from it. - Mark Twain
40. 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. - Voltaire
41. And if there were a God, I think it very unlikely that He would have such an uneasy vanity as to be offended by those who doubt His existence. - Bertrand Russell
42. 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? - Epicurus
43. I'm a polyatheist - there are many gods I don't believe in. - Dan Fouts
44. If it turns out that there is a God, I don't think that he's evil. But the worst that you can say about him is that basically he's an underachiever. - Woody Allen
45. A lie is a lie even if everyone believes it. The truth is the truth even if nobody believes it. - David Stevens
46. Men rarely (if ever) manage to dream up a God superior to themselves. Most Gods have the manners and morals of a spoiled child. - Robert A Heinlein
47. I refuse to prove that I exist," says God, "for proof denies faith, and without faith I am nothing. - Douglas Adams
48. It ain't the parts of the Bible that I can't understand that bother me, it is the parts that I do understand. - Mark Twain
49. He that will not reason is a bigot; he that cannot reason is a fool; he that dares not reason is a slave. - William Drummond
50. Remember, Jesus would rather constantly shame gays than let orphans have a family. - Steven Colbert
51. Which is it, is man one of God's blunders or is God one of man's? - Friedrich Nietzsche
52. Religion does three things quite effectively: Divides people, Controls people, Deludes people. - Carlespie Mary Alice McKinney
53. Religion has caused more misery to all of mankind in every stage of human history than any other single idea. - Anonymous
54. When a man is freed of religion, he has a better chance to live a normal and wholesome life. - Sigmund Freud
55. They felt that science would be corrosive to religious belief and they were worried about it. Damn it, I think they were right. It is corrosive to religious belief and it's a good thing. - Steven Weinberg
56. Take from the church the miraculous, the supernatural, the incomprehensible, the unreasonable, the impossible, the unknowable, the absurd, and nothing but a vacuum remains. - Robert G. Ingersoll
57. History teaches us that no other cause has brought more death than the word of god. - Giulian Buzila
58. Atheism is a non-prophet organization. - George Carlin
59. We are all atheists about most of the gods that societies have ever believed in. Some of us just go one god further. - Richard Dawkins
60. A believer states everything must have a creator but fail to say how he was created. - Anonymous
61. "There are no atheists in foxholes" isn't an argument against atheism, it's an argument against foxholes. - James Morrow
62. People will then often say, 'But surely it's better to remain an Agnostic just in case?' This, to me, suggests such a level of silliness and muddle that I usually edge out of the conversation rather than get sucked into it. (If it turns out that I've been wrong all along, and there is in fact a god, and if it further turned out that this kind of legalistic, cross-your-fingers-behind-your-back, Clintonian hair-splitting impressed him, then I think I would choose not to worship him anyway.) - Douglas Adams
63. Properly read, the bible is the most potent force for Atheism ever conceived. - Isaac Asimov
64. If all the Christians who have called other Christians "not really a Christian" were to vanish, there'd be no Christians left. - Anonymous
65. An atheist is a man who has no invisible means of support. - John Buchan
66. Gods dont kill people. People with Gods kill people. - David Viaene
67. If God were suddenly condemned to live the life which He has inflicted upon men, He would kill Himself. - Alexandre Dumas
68. Atheism is nothing more than the noises reasonable people make when in the presence of religious dogma. - Sam Harris
69. I don't believe in God because I don't believe in Mother Goose - Clarence Darrow
70. No philosophy, no religion, has ever brought so glad a message to the world as this good news of Atheism. - Annie Wood Besant
71. I refuse to believe in a god who is the primary cause of conflict in the world, preaches racism, sexism, homophobia, and ignorance, and then sends me to hell if I'm 'bad'. - Mike Fuhrman
72. Faith does not give you the answers, it just stops you asking the questions. - Frater Ravus
73. Believing there is no God gives me more room for belief in family, people, love, truth, beauty, sex, Jell-o, and all the other things I can prove and that make this life the best life I will ever have. - Penn Jillette
74. Absolute faith corrupts as absolutely as absolute power but absolute power is corrupt only in the hands of the absolutely faithful. - Anonymous
75. Gods are fragile things; they may be killed by a whiff of science or a dose of common sense. - Chapman Cohen
76. The inspiration of the bible depends on the ignorance of the person who reads it. - Robert G. Ingersoll
77. When one person suffers from a delusion, it is called insanity. When many people suffer from a delusion it is called religion. - Robert Pirsig
78. I wonder who got the shit job of scouring the planet for the 15000 species of butterfly or the 8800 species of ant they eventually took on board Noah's Ark. But at least we got that magical rainbow for all their trouble. - Azura Skye
79. I have no need for religion, I have a conscience. - Anonymous
80. Man has always required an explanation for all of those things in the world he did not understand. If an explanation was not available, he created one. - Jim Crawford
81. I am against religion because it teaches us to be satisfied with not understanding the world. - Richard Dawkins
82. What has been Christianity's fruits? Superstition, Bigotry and Persecution. - James Madison
83. The characters and events depicted in the damn bible are fictitious. Any similarity to actual persons, living or dead, is purely coincidental. - Penn and Teller
84. If god is the alpha and the omega. The begining and the end, knows what has passed and what is to come, like it states in the bible, why do people pray and think it will make any difference. - Mark Fairclough
85. The finality of death is the coldest truth one must face. Religion makes the perfect distraction. - Anonymous
86. Religion is the opiate of the masses. - Karl Marx
87. If God created the world, then who created god? and who created whoever created god? So somewhere along the line something had to just be there. So why can't we just skip the idea of god and go straight to earth? - Ryan Hanson
88. If we expect God to subscribe to one religion at the exclusion of all the others, then we should expect damnation as a matter of chance. This should give Christians pause when expounding their religious beliefs, but it does not. - Sam Harris
89. Atheists will celebrate life, while you're in church celebrating death. - Anonymous
90. Animals do not have gods, they are smarter than that. - Ronnie Snow
91. I have observed that the world has suffered far less from ignorance than from pretensions to knowledge. It is not skeptics or explorers but fanatics and ideologues who menace decency and progress. No agnostic ever burned anyone at the stake or tortured a pagan, a heretic, or an unbeliever. - Daniel Boorstin
92. I have never seen the slightest scientific proof of the religious ideas of heaven and hell, of future life for individuals, or of a personal God. So far as religion of the day is concerned, it is a damned fake… Religion is all bunk. - Thomas Edison
93. Fundamentalism, of any type, due to its prerequisite lack of intelligent thought, could prove to be the worst weapon of mass destruction, of all. - David J. Constable
94. To really be free, You need to be free in the mind. - Alexander Loutsis
95. Most religions prophecy the end of the world and then consistently work together to ensure that these prophecies come true. - Anonymous
96. Jesus hardly made the greatest sacrifice. He knew he would be resurrected anyway. - Anonymous
97. Religion is like a virus that affects the behaviour of its host in such a way as to propagate itself further. - Jack Pritchard
98. Religions are like pills, which must be swallowed whole without chewing. - Anonymous
99. Today's religion will be the future's mythology. Both believed at one time by many; but proved wrong by the clever. - Steven Crocker
100. The Bible - A Fairytale book of rules brainwashing millions. Obliviously used to help create war, kill, hate, judge and discriminate. - Anonymous
101. Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too? - Douglas Adams
Please feel free to comment on these quotes, and inform me of the authors of any I have misquoted or marked as "Anonymous". There are so many sources for these quotes it's hard to keep track of who really said what!