Was the grace doctrine given to Paul separate from Judaism or an extension of it?
The grace doctrine revealed to Paul was completely separated from Judaism, yet also an extension of it. It did not cancel what had gone before; it built upon it. Scripture unfolds by progressive revelation, so the revelation given to Paul was distinct from Judaism while still connected to God's prior dealings.
Les explains that God revealed the whole sphere of doctrine called grace, and it was completely separated from Judaism, and yet an extension of it. Les ties this to progressive revelation: everything in Scripture is progressive revelation. When Paul receives these revelations, that does not cancel everything that has gone before; it builds on it. Les illustrates with the Abrahamic covenant and Israel, and notes that after Israel rejected the Messiah according to prophecy, God saved Paul and sent him far hence to the Gentiles. Jesus did not teach the Twelve to go to the Gentiles with the gospel based on His death, burial, and resurrection because it had not yet happened. Paul’s message, however, centers on that death, burial, and resurrection. Thus the grace doctrine given to Paul is distinct from Judaism, yet connected to it as an extension.