Paul Gauguin exhibited as an Impressionist before moving on to his own style. Unsatisfied with Impressionism as it currently stood, he began work on developing new ideas inspired by the Japanese woodblock prints which had been so inspiring to his contemporaries, finding within them not merely a lack of spatial construct but a cultural tone of symbolic significance. He saw that the way in which something was painted communicated ideas about that thing, and that through art painters possessed greater liberties in communicating with an audience because they could not only paint selected scenes and items but could paint them stylistically. In effort to push Impressionism forward, then, Gauguin joined the artistic school of the Symbolists. Symbolism was, essentially, the artistic theory that art could, given its unique medium for creative expression, and should, given artists' higher calling to record truth around them, concern itself chiefly with the representation of intangible truths and ideas that could be expressed in no other ways. To put it in terms of an example, no other medium could, theoretically, put an image to the abstract quintessence of, say, love or sorrow. A painting could, in effect, record such a thing. These artworks could be symbols of the immaterial aspects of everyday life in the way that Impressionism was about recording visually the scenes of everyday life among the multitude. These paintings, therefore, frequently show angels or representative beings like Death, Wisdom, et cetera (just what Courbet promised he would never paint).
With these motivations, then, Paul Gauguin painted The Yellow Christ, a totally new look at an old topic: the Crucifixion. We can see immediately that the artist has painted this scene in a wholly untraditional light. It has been stripped of its realism and painted with the simplicity of cartoon imagery. What's more, the scene itself appears toned down, and the thematic material, softened up. Never has the Crucifixion looked so pacified and tame. There is no blood in the painting, and Christ's crown of thorns is noticeably missing. The expression on Jesus' face seems to be one of calm relaxation, not excruciating agony. Golgotha, the place of our Lord's death, has here been changed to a peaceful, pastoral setting, filled with rich, red autumn trees (which, by the way, form hearts). And replacing the mocking crowd of jeering spectators is a group of humble nuns who quietly accept the scene with some passivity. Some people are offended by this painting. It almost looks sacrilegious. Just what is the artist doing here?
As a Symbolist, Gauguin painted the qualities of ideology attached to a subject matter within a painting of that subject. When considering the sufferings of Christ on the cross he thought of the widely instituted religious connotations that such a scene had come to signify in his contemporary culture; that Christ's Passion was an expression of His love, and that His death was a gift bringing peace and redemption to those who would put their faith in Him—(haven't researched Gauguin's personal religious beliefs, so don't misinterpret me; this is a staple of broader Christendom at that time, not necessarily his own convictions). Therefore, the death of Christ represents something sweet to the Believer, something in which he can take comfort and look to with fondness—(and, by the way, these ideas are not expressive of my own beliefs either, let it be clearly noted). Through Symbolist style, then, the artist sought to re-imagine the Crucifixion in the way people tended to think of it, or respond to it: with sentimentalism. That is why it does not appear realistic. The intensity of the colors (their brightness and purity) is exaggerated because the event has so starkly continued on into the Modern world in its telling and retelling, losing (allegedly) its accuracy over the years and entering into the category of traditional folklore or childlike faith, rather than splendorous revelation of profound truth, like the Renaissance artists portrayed it as. Everything is moderated here. Do you remember Grunewald's depiction of the Crucifixion? Compare that to this, and the difference goes beyond black-and-white extremes. Religion, however, had grown to become the societal institution for moral order and peaceable courtesy. In the Victorian Age, a "good Christian man" came to mean a well-behaved, genteel man of upstanding character and reputation; it was something respectable, temperate, and nice, so no wonder this Symbolist representation of the Christian faith is painted with such gentleness and pleasantness of form. Christ's love, forgiveness of sin, reconciliation with God the Father are all positive things; so why paint a Crucifixion scene that's depressing, violent, and austere? (These are some of the notions of the Symbolist art theory behind this painting).