“Ok, so there is truth outside of your Church?”
There may well be. I don’t think The Church speaks to that. For example, The Church cannot say that there is no salvation outside The Church since The Church cannot and does not determine whither the Spirit goes. The Church does say that all that is necessary for theosis is found within The Church.
Nor are they qualified to say who does or who does not. We see in the examples from Numbers 11 that even those with the HS resting on them couldn't tell that those outside their group had it.
In Luke 9, we see that Jesus Himself, sends out the 12 Apostles to preach, and here they come in verse 9:49, saying "Master, we saw one casting out devils in thy name; and we forbad him, because he followeth not with us."
Notice whom the one was not following.
The Mormons claim to have captured the HS in a jar like a lightning bug and only their priests can parcel Him out. Perhaps in the BOM, Jesus says "And I saw the HS fall like a lightning bug from heaven", I don't know, but it's just an example that no one group has all the truth no matter what they claim.
The only Truth we can be sure of is the truth in God's Word, given to all of us.
So anyway, to say that discussing the Word of Truth outside of the opinion of your church fathers, "is fruitless" could just be a hindrance in going up that ladder of yours.