That is the foundational motivation for Mormonism. Traditional Christianity had so devolved from the true faith that it was necessary for Joseph Smith to bring correction. Do you disagree with that? Why was it necessary for JS to show up on the scene? Did he not introduce anything new?
You said: “You yourselves admit that your doctrines about Jesus are incompatible with the doctrines of Jesus conveyed through Scripture.”
Then, I said: “I never admitted that.”
Then you said: “Traditional Christianity had so devolved from the true faith that it was necessary for Joseph Smith to bring correction. Do you disagree with that?”
No, I don’t disagree. The logical flaw that you embrace is in assuming that traditional Christianity is compatible with the doctrines Jesus conveyed through scripture.
~”Why was it necessary for JS to show up on the scene?”~
Because man has, in many cases, made up doctrines to suit him, rather than holding with what Christ and the prophets taught.
~”Did he not introduce anything new?”~
There are components of LDS theology that were held in reserve for the end times; the core Gospel, however, is precisely as it always has been. In that regard, Joseph Smith did not introduce anything new - he simply acted as God’s instrument to reintroduce what man had abandoned.