Why did Jean Paul Sartre turn a believer prior to his death?

This might sound shockingly upsetting to the legions of admirers of the doyen of Existentialism or Western Alienation but to quote T S Eliot from his 'Burnt Norton': 'Humankind cannot bear very much reality.' We indeed can't, especially when the reality is so full of disillusionment, leaving us disenchanted.

It's interesting to observe that only three out of a series of Existentialists were atheists in the real sense of the term. Those three were Jean Paul Sartre, his partner Simone de Beauvoir and another great French, Albert Camus. All other Existentialists like Soren Kierkegaard, Martin Heidegger, Karl Jaspers, Martin Buber, Frantz Fanon, Ralph Ellison, among others were either believers, skeptics or agnostics. Nietzsche was not exactly an Existentialist. He was a Nihilist. 

Camus went beyond atheism. In today's parlance, he was an apatheist (a person who goes beyond theism and atheism). 

Contrary to the general belief that Sartre was an atheist right from the beginning, he was extremely confused about his religious beliefs right from his childhood. His Atheistic Existentialism was actually a façade. It was an edifice. He was religiously vulnerable and spiritually susceptible. Those who've studied his Existential philosophy and read all his books (esp. in French) viz., 'Nausea', 'The Wall', 'Existentialism is humanism', 'Being and Nothingness', 'The Reprieve', 'The Age of Reason,' to name but a few, find excessive atavistic antagonism towards god, which prompted Camus to comment in Le Monde in 1949, 'To me, Sartre's excessively rabid stand against god is an ontological proof of his deep-down faith in some creator. The man (Sartre) is a closet believer who'll die not as an atheist but as a believer.' So prophetic!

Tom Flanley of Cambridge University closely studied Sartre's personality, his persona and all his writings and opined that 'Sartre suffered from 'Excess Reverse Syndrome' (ERS). To make it easier for the readers, 'Where there's excessive hatred, there's love lurking somewhere.' What we deny all the time is actually our subconscious belief that's fighting to come out as our faith.' To deny is to accept unwittingly. This happened to Sartre. He kept condemning god but god resided in the crevices of his mind. On the contrary, Camus didn't bother about the existence or non-existence of god. It was a non-entity to him. Read his books, 'The Stranger', 'The Plague', 'The Myth of Sisyphus', 'The Fall', 'The Rebel', 'The Happy Death', 'The Guest,' et. al., god's a maginalised entity that seldom appears as a character or a metaphor. To quote Camus in Le Parisien (1953), 'I'm theologically indifferent to god and religion and spiritually casual about any esoteric belief(s). I've no time to think or condemn god.'

But this wasn't the case with Sartre. He was ostensibly obsessed with the 'non-existence' of god and his atheism bordered on militant atheism of today's Richard Dawkins, Sam Harris, Salman Rushdie and Christopher Hitchens. It was a pathological negation of god that was bound to recoil and re-blossom into equally strong faith in god. That's why he called out to a priest just prior to his death. Dismayed, his followers asked him as to what happened to him when death was at his doorstep. His reply was, 'In case.........'

The one who revealed Sartre’s astonishing change was his friend and ex-Maoist, Pierre Victor (A.k.a. Benny Levy), who spent much of his time with the dying Sartre and interviewed him on several of his views. According to Victor, Sartre had a drastic change of mind about the existence of god and started gravitating toward Messianic Judaism. This is Sartre’s before-death profession, according to Pierre Victor: “I do not feel that I am the product of chance, a speck of dust in the universe, but someone who was expected, prepared, prefigured. In short, a being whom only a Creator could put here; and this idea of a creating hand refers to god.”

This statement effectively closes Sartre’s existential phase to the consternation of his followers and his lover, Simone de Beauvoir, in particular. During Sartre’s funeral, De Beauvoir reportedly behaved like a bereaved widow, but later became quite critical of Sartre in her “Cérémonie Des Adieux.” Later on, she revealed her anger at his change of mind by stating, “How should one explain this senile act of a turncoat? All my friends, all the Sartreans, and the editorial team of Les Temps Modernes supported me in my consternation.”

This is how the cookie crumbles. Even the best of minds may change their life-long well-guarded belief systems when death hovers over their heads. Sartre was no exception. To quote Camus from his 'The Happy Death': "Death has the power and audacity to change one's beliefs." It did change his friend and fellow Existentialist Sartre's unbelief.