i) It violates Nicean principles of Episcopal Diocesan integrity
You know this one because the Windsor Report itself refers to this in response to some actions of other Primates outside TEC. Simply put, the Council of Nicea ruled that in one place there would be one bishop and one diocese. It was not possible to have two bishops in jurisdiction over one diocese or place within the diocese.
Interestingly though, the out working of this ruling was to, over time, depose a great number of Arian Bishops and to replace them with orthodox episcopal authority. We also have the very important example of St John Chrysostom who as Patriarch in Constantinople deposed a number of unorthodox bishops. He didn’t put up parallel jurisdictions, he deposed them.
The bottom line is that a parallel province is un-Nicean and therefore unCatholic. It destroys the principle that there is a universal church represented by universally recognised bishops.
ii) It doesn’t discipline TEC
So this leads us to our second problem with a parallel or two province solution - it doesn’t discipline TEC for it’s apostasy. We need to remember that this is not a squabble over adiaphora or women priests. It’s not really about homosexuality actually. The problem with 815 (the TEC headquarters and leadership) is that it has completely apostasised. KJS and others, starting with Pike and Spong and carried on down the decades, simply refuse to affirm and teach basic Christian truths. Spong denied the entire Nicene Creed and yet TEC did nothing about it. In St John Chrysostom’s day Spong would have been literally kicked out the palace gates.
By this logic, Nicea doesn’t permit denominations either. For example, there is a Roman Catholic Bishop and Diocese in New York, an Episcopal Bishop and Diocese in New York and a Greek Orthodox Bishop and Diocese in New York, as well as others.
It is ironic for “progressives” to be appealing to a council that occurred 1700 years ago, and the other work of which is ignored and trampled upon.