I think that what PerCrucem is trying to say is that:
In our individual process of discernment, we (Catholics) reached the conclusion that the Catholic Church is the One Church. We still go through the individual process of discerning the truths and revelations given to us.
The biggest problem with the One Church argument with PerCrucem (And other Lutherans like him) is that he does not see himself [apart] from us, but just [not in communion] with us.
An Orthodox person will reach his/her own individual conclusion.
Others that don’t weight history and apostolic succession as we do, don’t really take into account these elements like we do.
Please be mindful that I am not advocating a relativistic Church. But that we go through an individual discernment process as much as they do.
PS - I have this whisper in my ear:
There can only be one
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