The first clue I got was several years ago in a footnote in the catalogue for the 1996 Cézanne exhibit that was in Philadelphia. The footnote spoke of Cézanne leaving a Mass because he didn’t like the organ music being played. So Cézanne attended Mass? Did he go regularly? Was he a member of the Catholic Church? No other mention of his religion could be found in this book.
Recently, I checked out a copy of Conversations with Cezanne edited by Michael Doran. A wonderful book of original source material: Cézanne letters and recorded conversations with him. In reading the original source material it became very clear: Cézanne was raised a Catholic in the south of France, Aix-en-Provence. As a young man he joined in the bohemian life style when he moved to Paris. In 1891 under the influence of his sister he returned to the Catholic Church and eventually partook of the sacrament of confessions and the Eucharist.
One conversation recounts how his religious scruples prevented him, an old man by then, from hiring nude female models, as he was afraid of causing scandal in his community. His bathers paintings were done from either old sketches or male models.
We all acknowledge Cézanne as a true genius but not much of that recognition came during his life. That did not bother him though as his chief battles were all internal. He never felt he had actualized the vision that he had for making art. He always felt he was improving but he never arrived.
His friend and confidant Emile Bernard, himself an artist and Christian, had this to say about Cézanne. He has just finished having supper with Cézanne and is about to depart for Paris leaving Cézanne virtually alone. He is meditating on Cézanne's life:
When I arrived back home I was filled with sad thoughts of a life consecrated entirely in its sincerity and its wisdom to civilized man’s most noble ambition, to art, and nevertheless he found only derision, scorn, exhaustion, dissatisfaction, and death. No doubt, glory will come some day, late, disputed, focusing on the unshaken effort of this superior intelligence, but a glory abominably travestied by the speculator and distorted by a critical response until that moment mute, then becoming self-interested and venal, In the face of so much sadness and emptiness, hope came to me like a caress, to awaken my heart: Cézanne was a Christian! Surely in a better world, he will find recompense for the life he offered with the sublime self-abnegation of a martyr.
From Memories of Paul Cézanne by Emile Bernard published in Conversations with Cézanne.
Perhaps because Cézanne's work is always referred to as spiritual and not religious the apparent connections between his faith and his painting do not seem to be important. In a letter to his niece he sends regrets that he and his family cannot attend her first communion service because they are too far away, in Paris. Cézanne asks her to pray for him:
I ask you to pray for me, for once old age has caught up with us we find support and consolation in religion alone.
From Paul Cezanne, Letters edited by John Rewald
I have always found Cézanne's painting deeply spiritual and immensely satisfying. Now I find it even more so to know that he is a part of the Church and has been ultimately rewarded for his struggles and work.