For me the answer has always been obvious, for Scriptural reasons. Jesus did not say, "on this rock, I will build my churches." He said, "my church." In the beautiful letters to the Ephesians and the Colossians, it is revealed that the one Church is the eternal bride of Christ, chosen in Him before the world began, to be holy and blameless in His sight.
In the Creed, two of the "marks of the Church" speak directly of its unity: it is One, and it is Catholic, which means universal. In the Creed settings of William Byrd's Masses, the word "catholicam" is treated with special care--and often repeated.
It is not coincidental that the integrity of this bride is being threatened when marriage itself is also under direct attack.
One of the great theologians of our times, Avery Cardinal Dulles, discussed the ins-and-outs of the whole matter with his customary courtesy and clarity.
"The ontological priority of the Church universal appears to me to be almost self-evident, since the very concept of a particular church presupposes a universal Church to which it belongs, whereas the concept of the universal Church does not imply that it is made up of distinct particular churches.
"Historically, too, the priority of the universal Church is evident because Christ unquestionably formed the community of the disciples and prepared the apostles for their mission while they were still gathered together. Particular churches emerged only after the Church became dispersed, so that it became necessary to establish local congregations with their own hierarchical leaders."The whole article is worth reading. Among other things, it shows that at the time of his writing, almost 15 years ago, the breakup of the Church was also "necessitated" by the same moral issues that are being used as the wedge that threatens to divide and conquer us today.
Continuing his critique, Cardinal Dulles states: "Kasper maintains that Ratzinger proceeds by Plato´s method, starting from universal concepts rather than, as Kasper prefers, taking the universal concept as a mere abstraction from concrete reality, which is particular. I suspect that Ratzinger has a certain affinity for Christian Platonism, but in the present debate he takes his arguments from Scripture and tradition rather than from Platonic philosophy. He makes it clear that the universal Church animated by the Holy Spirit exists here on earth, within history. In an unsigned article published a year after Communionis notio, commonly attributed to Ratzinger, the author insists that there can be nothing more concrete than the gathering of the 120 at Jerusalem."
At another point, Dulles focuses on key phrases in the Second Vatican Council´s dogmatic constitution on the Church, "Lumen Gentium."
"Kasper states correctly," he writes, "that according to Vatican II the bishop receives his office of government (munus regendi) directly from Christ through the sacrament of ordination (Lumen gentium 21), but he fails to note that the bishop cannot govern a particular diocese unless he is duly appointed by canonical mission and remains in hierarchical communion with the college of bishops and its head, the bishop of Rome (Lumen gentium 24). The bishop´s powers of teaching and government ´can be exercised only with the consent of the Roman pontiff´ (Lumen gentium 22)."