After the First World War, several Catholic authors such as François Mauriac, Paul Claudel, Charles Péguy and Georges Bernanos sought to express their Christian sensibility in their works. The themes that characterise the works of the Christic pioneers of this period respond to the religious demands and concerns of the time: vocation, grace, sin, but also loneliness, agony, death, etc. By embodying religious themes in the lives of their main characters, they succeeded in showing the suffering of humanity in a world without God. This work, which deals with a subject on religious themes among French writers of the 20th century, is divided into five parts and aims to analyse the thematic material of the selected works of the four Catholic novelists of the 20th century: Paul Claudel, François Mauriac, Charles Péguy and Georges Bernanos in order to discover the role and importance of the religious thoughts and themes that dominate them. Thanks to these themes, we can prove how these religious novelists succeeded in reviving Christianity in the world of the 20th century, which has lost its colours and religious foundations.