"We, therefore, have a combination of assumptions being combined to create a doctrine."
No, the facts of the case and hence the doctrine existed prior to the assumptions. The assumptions are merely explanations of the doctrine.
"It certainly is not authoritative."
Correct - for you! But as you are extra ecclesiam, you hold an a priori rejection of external authority anyway. Do you believe that anything is binding?
By and large, this should be a catholic thread, however, the title indicated an explanation was being proffered.
I assumed that explanation wasn't really to the faithful, but to those outside your denomination. (In other words, the title appears that the article intends to preach to outsiders and not to "the choir.")
Nonetheless, I wish to allow this thread to remain catholic after having made my contribution.
As a summary, it speaks for itself.
As a Christian, I believe that the best position to be in would be one in which the body was in both a spiritual apostolic lineage and in a successive apostolic lineage.
I have a very high view of the church universal, I think.