Who was the greatest atheist philosopher in your opinion?

Ayn Rand, for re-establishing Aristotelianism into philosophy, and for saying Aquinas started the Renaissance. "The Renaissance was specifically the rebirth of reason, the liberation of man’s mind, the triumph of rationality over mysticism—a faltering, incomplete, but impassioned triumph that led to the birth of science, of individualism, of freedom."

"The liberation was not total, nor was it immediate: the convulsions lasted for centuries, but the cultural influence of mysticism—of avowed mysticism—was broken. Men could no longer be told to reject their mind as an impotent tool, when the proof of its potency was so magnificently evident that the lowest perceptual-level mentality was not able fully to evade it: men were seeing the achievements of science."

http://aynrandlexicon.com/lexicon/renaissance.html

Oh, she never said science was perfect, or the be-all-and-end-all of life. I remember she criticized Einstein for leaving physics with more questions and for claiming that he didn't know the answers. And yet we take it on "faith" that Einstein was right---we just have to figure out "how" he was right?

She saw that science was faltering, and taking civilization down with it.

"in the field of scientific theory, unable to integrate or interpret their own data, scientists are abetting the resurgence of a primitive mysticism. In the humanities, however, the crash is past, the depression has set in, and the collapse of science is all but complete.

The clearest evidence of it may be seen in such comparatively young sciences as psychology and political economy. In psychology, one may observe the attempt to study human behavior without reference to the fact that man is conscious. [Note: this has changed. When she wrote that, Behaviorism seemed to be in the ascendancy.] In political economy, one may observe the attempt to study and to devise social systems without reference to man. [This has not changed: Obama thinks you can spend what you haven't got by trillions, and then just print it. He acts as if wealth is a 'sure thing', a 'static' thing that Man has that merely comes and goes like mushrooms in the night and all we have to do is wait for the right night to harvest them.]

http://aynrandlexicon.com/lexicon/science.html

Bertrand Russell. Without a shadow of a doubt.

The vast majority of modern (i.e. 20th and 21st century) analytic philosophers are atheists. Most of them don't write on atheism though; it's not very interesting to talk about, compared to problems in epistemology, logic, language or metaphysics.

Thomas Hobbes. In 17th century England you had to be cautious about the degree of explicitness you gave your arguments for atheism, but it was not far from the surface in Hobbes' case, and he connected it with a broader nominalist and materialist world view in a fascinating way.

Hume, Russell, Nietzsche... and so on... and so on = Dennet, Churchland, Churchland, Searl, Fodor, Blackburn, Davidson, Quine, Williams, Carnap... and something of the present day philosophers of the Western analytic custom which you stumble on in maximum universities. honestly ninety% of expert philosophers are atheists. they're in basic terms satisfied to enable others do the grimy paintings for them. they have lots extra pressing matters to attend to. Freddy pronounced it ultimate whilst he pronounced that: "there's a great ladder of religious cruelty with many rungs; yet 3 of them are the main necessary. At one time one sacrificed human beings to one's god, possibly precisely those human beings one enjoyed ultimate —the sacrifice of the 1st-born present in all prehistoric religions belongs right here, as does the sacrifice of the Emperor Tiberius in the Mithras grotto on the isle of Capri, that maximum terrible of all Roman anachronisms. Then, in the ethical epoch of mankind, one sacrificed to one's god the main effectual instincts one possessed, one's `nature'; the exhilaration of thin pageant glitters in the merciless look of the ascetic, the stimulated `anti?naturist'. ultimately: what substitute into left to be sacrificed? Did one not ultimately could desire to sacrifice each thing comforting, holy, therapeutic, all desire, all faith in a hid solidarity, in a destiny bliss and justice? Did one not could desire to sacrifice God himself and out of cruelty against oneself worship stone, stupidity, gravity, destiny, nothingness? To sacrifice God for nothingness—this paradoxical secret of the perfect act of cruelty substitute into reserved for the era this is even now bobbing up: all of us know something of it already".

Nietzsche, who infamously pronounced that 'God is Dead' (or was that taken out of context?). Anyway Mad magazine might be another who in turn said that 'God isn't Dead, he just got he Hell out of here.'

Hume.