Shaw's was raised as an Anglican, although Irish Anglicans were frequenly called "Protestants" instead of "Anglicans." As a child Shaw attended the Church of Ireland, which is an autonomous province of the Anglican Communion. Until he was about thirty years old, Shaw identified himself as an Atheist.
In the 1890s, Shaw renounced Atheism. He began identifying himself as a mystic. Some people believe Shaw was strongly influenced by Hinduism. Throughout the rest of his life, Shaw espoused a belief system that Sloan called "an idiosyncratic version of Henri Bergson's creative evolution." His self-described mystic beliefs focused on the evolution of humanity and other organisms, driven by a mysterious "life force." Shaw wrote explicitly about his beliefs, such as in "The New Theology" a 1907, and these beliefs also also espoused through his fictional plays.
From: Gary Sloan, "The religion of George Bernard Shaw: when is an Atheist?", published in American Atheist Magazine, Autumn 2004 (http://www.findarticles.com/p/articles/mi_m0OBB/is_4_42/ai_n8695811; viewed 24 October 2005):
...Shaw was an indefatigable crusader for social amelioration... he awakened complacent audiences to a host of social ills abetted by conventional morality, bourgeois respectability, and ossified institutions. "I was a social reformer and doctrinaire first, last, and all the time," he wrote. "I saw a way through the Valley of the Shadow and believed that when men understood their predicament they could and would escape from it." Enlivening didacticism with mordant wit, he dissected slum landlordism, prostitution, marriage, free love, politics, militarism, nationalism, jingoism, capitalism, evangelism, and other isms steeped in hypocrisy, cant, and deceit.
He was a lifelong socialist, vegetarian, and pacifist... As a leading pundit for the Fabian Society, Shaw was instrumental in the formation of the Labor Party, which assimilated the genteel form of Marxism espoused by Fabians.
His vegetarianism was actuated by an egalitarian view of species and concern for humanity. He envisioned a cortege of animals paying him posthumous homage: "My will contains directions for my funeral, which will be followed not by mourning coaches, but by herds of oxen, sheep, swine, flocks of poultry, and a small traveling aquarium of live fish, all wearing white scarves in honor of the man who perished rather than eat his fellow-creatures. It will be, with the exception of the procession into Noah's Ark, the most remarkable thing of the kind ever seen." A carnivorous lifestyle, he believed, coarsened sensibilities, squandered natural resources, and debased workers in the meat industry.
Shaw was reviled for his intransigent pacifism... On the eve of World War II, in a talk broadcast by the B.B.C., the octogenarian defended pacifism by citing the Gospels: "The pacifist movement against war takes as its charter the ancient document called 'The Sermon on the Mount.' The sermon is a very moving exhortation, and it gives you one first-rate tip, which is to do good to those who despitefully use you and persecute you. I, who am a much hated man, have been doing that all my life, and I can assure you that there is no better fun; whereas revenge and resentment make life miserable and the avenger hateful. The lesson we have to learn is that our dislike for a certain person, or even for the whole human race, does not give us any right to injure our fellow-creatures, however odious they may be."
Until he was thirty or so, Shaw called himself an Atheist. He became one, he later quipped, before he could think. He adjudged the doctrines of the Church of Ireland, which he attended as a child, unintelligible or absurd. Since the first of its Thirty-nine Articles describes god as "without body, parts, or passions," he waggishly theorized that the church was atheistic. An incomprehensible god, he opined, was tantamount to no god. In 1875, he blazoned his Atheism abroad. In a letter to Public Opinion, a Dublin newspaper, he "announced with inflexible materialistic logic, and to the extreme horror of my respectable connections, that I was an atheist." In Immaturity, the first of five novels he wrote in his twenties, the young protagonist, obviously Shaw's alter ego, walks pensively in the cloisters of Westminster Abbey: "His hushed step, impressive bearing, and reflective calm, marked him as a confirmed freethinker."
At a bachelor party, when someone alleged that a local infidel had been slain by a wrathful god, Shaw proposed to demonstrate "the absurdity of the belief in violent interferences with the order of nature by a short-tempered and thin-skinned supernatural deity." ...The host, fearing the impious challenge would precipitate a stampede of guests, forbade the experiment.
To save Shaw from hell-fire, a friend prevailed on a Roman Catholic priest to catechize the upstart Atheist. Having repaired with his catechumen to a church cell, the priest [argued with Shaw that the universe exists, thus somebody must have made it. Shaw countered that if that somebody exists, somebody must have made him, and the priest granted that there could be a maker of God. But, the priest countered, an infinite line of makers of God is unthinkable and extravagant, so he appealed to Shaw to believe in just one. Shaw said that it was just as easy for him to believe that the universe made itself.]
...Fifty years later, Shaw stuck to his guns. He told an interviewer for a church magazine: "A First Cause is a contradiction in terms, because in causation every cause must have a cause; and therefore there can no more be a First Cause than a first inch in a circle..."
...Shaw scoffed at superstition, churches, ecclesiastics, rituals, ceremonies, and creeds. In The Adventures of the Black Girl in Search for God, a sardonic tale published in 1933, he derided the myopic sectarianism that strews dissension among Christians...
Shaw favored parliamentary legislation to abrogate the Church of England. In "The Church Versus Religion," he limned the average rector as a bigoted today of secular power and privilege: "He claims and exercises all the liberties of a country gentleman, and wallows openly in class prejudices. Often he snubs the poor and sides with the squire against them; he sees to it that servility and imperialist militarism are inculcated in the Church schools; he pitches the emblems of Christian peace into the cellar and waves the Union Jack the moment there is any question of war; he supports the way of the police as God's appointed way of dealing with crime."
Shaw [in his writing] depicted the god of Abraham and Moses as a boastful, imperious, and sanguinary fiend.
While Jesus fared better than Yahweh, Shaw impugned the doctrines of atonement and universal love. Atonement he deemed "a demoralizing and unchristian doctrine, a means by which we cheat our consciences, evade our moral responsibilities, and turn our shame into self-congratulations by loading all our infamies on to the scourged shoulders of Christ." Vicarious remissions of guilt were inherently ignoble and unjust.
Notwithstanding his paean to "The Sermon on the Mount," Shaw considered it psychologically impossible to obey "the commandment to love one another." Humans weren't lovable animals: "If you tell me to be perfect as my Father in Heaven is perfect, I can only say that I wish I could. That is more politic than telling you to go to the zoo and advise the monkeys to become men and the cockatoos to become birds of paradise."
Even when he no longer thought of himself as an Atheist, Shaw lauded Atheists for clearing minds of theological rubbish: "The real religion of today was made possible only by the materialistic-physicists and atheistic critics who performed the indispensable preliminary operation of purging us thoroughly of the ignorant and vicious superstitions which were thrust down our throats as religion in our helpless childhood." Against an Atheism born of despair and anger, Shaw counterposed "the youthful atheism with which every able modern mind begins, an atheism that clears the soul of superstitions and terrors and servilities and base compliances and hypocrisies, and lets in the light of heaven."
In the 1890s, Shaw renounced Atheism and repackaged himself as a mystic. He also tinkered with his past. Now, his Atheism had not really been Atheism. He had called himself an Atheist only "because belief in God meant belief in the old tribal idol called Jehovah; and I would not pretend I did not know whether it existed or not." While Atheists still cleaned the Augean stables of superstition, they were now deemed "superficial and light-minded." They over-rated reason: "I exhausted rationalism at the age of twenty-four," Shaw told his friend Dame Laurentia McLachlan, an abbess, "and should have come to a dead stop if I had not proceeded to purely mystical assumptions." The roots of his mysticism stretched deeper and deeper: "I am, and I always have been, a mystic," he informed an audience in 1911. As an Irish Protestant, he was born to the manner: "The true Protestant is a mystic, not an Institutionalist."
Shaw's renunciation of Atheism was accompanied by sallies against scientific materialism. By undermining teleological conceptions of the cosmos, science eviscerated joy and hope: "If there is no purpose or design in the universe," Shaw told an audience, "the sooner we all cut our throats the better, for it is not much of a place to live in." At a toast to Einstein in 1930, Shaw polarized science and religion: "Religion gives us certainty, stability, peace. It gives us absolutes which we long for. Science is always wrong and never solves a problem without raising ten more problems."
Shaw skewered Darwinism [on philosophical and moral grounds]... Shaw began to spread "the Gospel of Shawianity." He evangelized for an idiosyncratic version of Henri Bergson's creative evolution, stripped of the Frenchman's lucubrations on space, time, duration, memory, and mind. From the first decade of the twentieth century to the end of his life, in speeches, essays, stories, letters, and plays, Shaw expatiated on the life force--a mysterious power, immanent in living matter, that supposedly drove evolution. Shaw reified the power as an inchoate deity struggling to actualize itself in organisms. Every species had been an instrument of its effort to acquire power, knowledge, and understanding. Through trial and error, at a laggard pace, it inched its way upward: "Conceive of the force behind the universe," Shaw said in "The New Theology," a 1907 speech, "as a bodiless, impotent force, having no executive power of its own, wanting instruments, something to carry out its will in the world, making all manner of experiments, creating reptiles, birds, animals, trying one thing after another, rising higher and higher in the scale of organism, and finally producing man, now and then inspiring that man, putting his will into him, getting him to carry out his purpose."
The life force exhorted humans to seek signs of cosmic intent: "Remember, you are not here merely to look after yourself. I have made your hand to do my work; I have made your brain, and I want you to work with that and try to find out the purpose of the universe." The life force esteemed self-sacrifice. In The Shewing-Up of Blanco Posnet, a play, the life force infiltrates the conscience of a disreputable horse thief who risks his life to save a child. Afterwards, the homespun thief edifies his cohorts: "You bet the Lord [aka the life force] didn't make us for nothing; and He wouldn't have made us at all if He could have done His work without us..."
...In Shawianity, god was a work in progress, not a fait accompli. In a 1909 letter to Leo Tolstoy, Shaw explained: "To me God does not yet exist; but there is a creative force struggling to evolve an executive organ of godlike knowledge and power; that is, to achieve omnipotence and omniscience; and every man and woman born is a fresh attempt to achieve this object. We are here to help God, to do his work, to remedy his whole errors, to strive towards Godhead ourselves." In its odyssey to achieve fruition, the life force would create ever-higher forms of humanity--supermen, super-supermen, supermen to the third power: "When one instrument is worn out, I will make another, and another, and another, always more and more intelligent and effective."
Shaw fused... the life force with the instrument. In "The New Theology," he prepped his audience: "When you are asked, 'Where is God? Who is God?' stand up and say, 'I am God and here is God, not as yet completed, but still advancing towards completion, just in so much as I am working for the purpose of the universe, working for the good of the whole society and the whole world, instead of merely looking after my personal ends."' God "would provide himself with a perfectly fashioned and trustworthy instrument. And such an instrument would be nothing less than God himself."
...Though [Shaw] ridiculed churches, clerics, orthodoxy, and anthropomorphic gods, he retained the moral fervor of his Protestant heritage. When hawking the life force and socialism, he was a holy prophet pitching the Kingdom of Heaven...
[Sloan concludes his lengthy essay about the religion of George Bernard Shaw (only excerpts from which appear hear) by opining:] So if, as theologians and philosophers have traditionally maintained, existence is a necessary attribute of god, Shaw qualifies as an Atheist, albeit an involuntary one.