Writers influenced by the "NPP" (New Perspective on Paul) tend to think that the soteriological pattern of religion was essentially the same between Second Temple Judaism and early Christianity. In other words, Judaism has never taught a "works-righteousness" soteriology but has essentially been a religion of grace from day one. Obviously this thesis has far too many flaws to count, and has not gone unchallenged by scholars from various creedal backgrounds.
One simple loophole that we shall examine today is the motif of Paul's hidden gospel (D.A. Carson has a wonderful essay on this and similar things in the Justification and Variegated Nomism series).
"Now to him who is able to establish you by my gospel and the proclamation of Jesus Christ, according to the revelation of the mystery hidden for long ages past...." (Rom. 16:25)
Obviously in this text both the gospel and the proclamation of Jesus Christ are understood to be revealed in a mystery that has been kept hidden throughout the ages. But of the content of this gospel can be contained within the word "grace" according to the apostolic kerygma (so Acts 20:24) , and this gospel has been hidden for long ages past, would it not follow that the grace revealed in the gospel was hidden before the time of Christ? And if such is the case, would this not also erect a vast disjoint between the soteriological understandings of ST Judaism and Christianity? This seems to be the scriptural teaching.