The research has been conducted as a continuation of the Merz Dissertation which has been complemented with the comparative study of Catholicism in the French and the Croatian literature of the first half of 20th century. The Dissertation compares, analyzes and gives a critical review of the works of the great French authors Paul Claudel, Georges Bernanos, Julien Green, François Mauriac, Charles Péguy and Francis Jammes as well as the famous Croatian writers Mate Ujević, Petar Grgec, Đuro Sudeta, Ivo Lendić, Štefa Jurkić and Nikola Šop. It emphasizes a close relationship between the literature of Šop and Jammes with regards to their long-standing correspondence. It also comments on the influence which the philosophy of Jacques Maritain, Emmanuel Mounier and Gabriel Marcel has on the above-mentioned writers and vice versa. It analyzes some of the works which in the best way represent catholic answers to the fundamental existential questions. It refers in particular to the problems of nature and grace. The literature of Croatian as well as French authors whose works it examines is such a distinctive occurrence that it is treated as a separate phenomenon. France as ‟‟the older daughter‟‟ of the Church, even in the critical period of ultra nationalism, the separation of church and state and Combesʼ attacks on the catholic religion maintains the continuity of the literary tradition. In Croatia, stronger Catholicism in literature is a reaction to the liberalism and anarchy in ethics and aesthetics. Catholic terms represent a huge challenge to skepticism which in that time prevails in science, literature and social mentality. What really stands out in the epoch of positivist determinism and rational materialism is the spirit. Narration of the supernatural requires the adjustment of the literary language and style which implies a solid grounding in the Catholic science. The whole social reality is judged through the prism of moral values. Realism is intertwined with idealism with the emphasis on the metaphysical hunger of the mankind for God. Literature spontaneously reflects the writer's mentality, sensibility, but also theologism with practicism. Characters, richly nuanced, are endlessly lively. False and hypocritical conformist piety is seen right through. Holiness is conceptualized mostly as the heroism of victory against sin. The literature of catholic modernism does not reject good fruits of modernist stylistics but combines them with traditional catholic motifs. The relation between truth, goodness and beauty is the fundamental criterion in the determination of the quality of literary works and their long-lasting and universal values.