The apse mosaic, created by the artist Salvatore Fiume is based on the theme of the "One, Holy, Catholic and Apostolic" church, in the light of the "Lumen Gentium": the cosmic church, i.e. that of yesterday, today and forever; the hierarchical and charismatic church together, the sacrament, in Christ, of the close bond between humanity and God.
This theme is written in golden letters along the side of the crown at the top of the mosaic: "Credo unam, sanctam, catholicam et apostolicam Ecclesiam."
Christ is at the centre extending his arms towards the whole of humanity who is walking towards him. Peter is at his side with the keys of the kingdom of God along with the Mary Immaculate Queen in the background. At the top, the eye of God and the Holy Spirit as a dove complete the trinity depiction. On the bottom right, the popes who governed the church from 1914 to 1968 are represented: Benedict XV, Pius XI, Pius XII, John XXIII and Paul VI.