The Roman basilica of Santa Sabina expresses well the specificity of the Christian foundation based on the teaching of the Apostles and the early Church's life.
This mosaic of two churches - the first, with mainly Petrine inspiration, from the Circumcision (cf. Col 4.10 to 11), that is, from the Jews of the land of Israel, the original disciples, believers in Jesus (Eph. 1:3 - 12), and the other, mainly Pauline, and thus also Jewish, but from the Jewish Diaspora, of the Jews scattered among the Gentile nations (Eph 1: 13-14), to which were added (prostitêmi: At 2,41.47; 5.14, 11.24) a crowd of so many men and women from paganism – which testifies that in Rome in the fifth century, it was still well known that the only people of the Lord was the breaking of the separation wall between Israel and the nations , operated by the blood of the Messiah Jesus, who has so reconciled both to God in one body through the Cross, announcing peace to those who were near and those who were far off (cf. Eph 2.11 to 22).
This means that the Christian faith, keeping our eyes fixed on Jesus, the origin and fulfillment of faith (Hebrews 12:2), not just continued to read the Hebrew Bible (the Tana "CH of Israel) together with the New Testament, but see the first result in perfect continuity of the second, and in the second recognizes the purest water coming from the source of the first.
Each attempt, open or subtle, to "replace" Rome with Jerusalem, the Christian Church with Israel, the New with the Old Testament, obscuring or deleting the latter is responsible for the heretical current "Marcionite" that has poisoned the faith and practice of Christians for centuries, both Catholic and Protestant or Orthodox, not taking into account, inter alia, that "the new covenant" was born and raised in the consciousness of Israel in the time of the Old Testament, and from the time of the prophecy of Jeremiah, between the beginning and the end of the Babylonian exile in the sixth century BC (Cf. Jer 31:31-34, Ezekiel 11, 14-21, 36, 24-38, 37.15 to 28, Isaiah 40-55, etc..). The decisive overcoming of such a substituted economy was proposed in the teaching of Pope John Paul II, but is still going on at the base of the Christian Churches. The Cathedral Church of Rome (the Lateran Basilica) can certainly stand as ‘omnium Urbis et orbis ecclesiarum Caput’, but not as their ‘Alma Mater’, as it reads on the label of inspiration "costantitiana" on its facade.