The Church started with 12 sinners who didn't stop sinning or stopped teaching because of it . Historical context can be read in light of what the Early Church Fathers have said . These documents, letters can be read today. they have a lot to say about how the content in the gospel should be understood .
The only content of the gospel is what is found in the Scriptures my dear friend. Please read and understand the words in the Scriptures themselves.
As we have said before, so now I say again: If anyone is preaching to you a gospel contrary to the one you received, let him be accursed.