Thank you for the response.
I understand how and some of the reasons why the monobishophoric system developed, especially in response to the threats of Marcionism and Gnostism. However, any Christian sect which fulfills the above would be a part of the universal church.
I'm afraid you can't get from Christ's approval of St. Peter's confession as the foundation of His Church to an assertion that accepting that confession is sufficient as a definition of encorporation into Christ's Church.
Arius accepted that Jesus Christ was the Son of God, but misunderstood His Sonship as the Divine Logos being the first creature. Nestorius accepted His Sonship, but divided the Divine Logos from 'the one from the Virgin'. Eutyches accepted Christ as the Son of God, but denied the reality of His humanity. (I will not continue the catalog of classical christological heresies--you get the idea.)
The succession of priests, from the very see of the Apostle Peter, to whom our Lord, after His resurrection, gave the charge of feeding His sheep, up to the present episcopate, keeps me here. And at last, the very name of Catholic, which, not without reason, belongs to this Church alone, in the face of so many heretics, so much so that, although all the heretics want to be called Catholic, when a stranger inquires where the Catholic Church meets (2), none of the heretics would dare to point out his own basilica or house (3). (Augustine,Against the Letter of Mani, AD 396-397)