All of the New Testament writings about these problems were directed to local churches while also being shared with all of the churches in order for them to learn as well.
Today’s denomination are based on an anti-Biblical idea of hierarchical authority structures in which local churches are controlled by church leaders who operate at some remote location. I believe Methodist churches operate this way.
So he is giving bad counsel not to leave denominations that turn against God. Start by being part of a local church that uses the Bible as the final authority for all disputes. If they abandon the Bible, go somewhere that clings to it.
Well said.