“If adding a nickle to what money I have gives me enough to purchase a particular thing, does that mean all I ever needed was a nickle? / Any doctrine that was unheard of until the middle ages is no doctrine of Christianity.”
Ummm...first, you aren’t adding a nickle to what you already have. You have nothing, and God provides what you need. And if a nickle or $5 was sufficient to buy object A, then yes, to buy object A all you need is there.
In this case, all you need for salvation and to be equipped for every good work is found in scripture.
Nor was the doctrine unheard of until the middle ages. The Apostles and even Jesus, when challenged, replied with scripture. When Satan challenged Jesus, Jesus replied with scripture.
And when the Apostles were challenged as they preached, they used scripture to back them up. And they commended those who DID search the scriptures to see if they were telling the truth. They did NOT reply, “Pope Peter, Vicar of Christ, says so!”
Finding final authority in scripture is a practice found repeated in scripture, with Jesus and the Apostles as our example.
You will also find the early church fathers repeatedly appealing to scripture for authority.
If you should find someone who does not yet believe in the gospel what would you [Mani] answer him when he says, “I do not believe”? Indeed, I would not believe the gospel myself if the authority of the Catholic Church did not move me to do so.
-St. Augustine, Against the Letter of Mani Called ‘The Foundation’ 5:6, AD 397)
Do you really think that mangling my analogy makes your proposition any less absurd?
In this case, all you need for salvation and to be equipped for every good work is found in scripture.
If that were true, show me the verse that explains the Trinity, and need to believe in it even if one does not understand it.
Nor was the doctrine unheard of until the middle ages.
Then you should have no problem citing it as a doctrine agreed upon by the Church fathers instead of reading it into anecdotes. What was this doctrine called before sola scriptura was named at the reformation if it wasn't a "new revelation?"