So I know I promised to shut up about this a while back, but I just thought it was interesting that Avery Cardinal Dulles, SJ (God rest his soul) stated that the problem with Protestant-Catholic ecumenism wasn't necessarily their beliefs on Justification as much as it was their worry about the issue of justification at all.
For Protestants Justification is the doctrine upon which the Church stands or falls, because Justification causes the Church to exist. For Catholics Ecclessiology is the doctrine upon which the Church stands or falls, because it is the doctrine about the Church itself. Our starting points are so different that it's no wonder we get to different conclusions.
Personally I think all the scripture is a red herring, as the NPP has pretty much raped Luther's exegesis. And as the "New" perspective on Paul is just the Old Catholic perspective, we've pretty much gone full circle. The real issue like I've said, is where you start, which doctrine is most important, and epistemology (How do you know what is true?)
Catholicism starts with Metaphysics for it's epistemology - Aristotle/Aquinas - which is the worst of all sins to the Reformers. Reformers start with Ockham and Fideism.
It's two different languages, two different gospels, two different histories.
It reminds me of the category for divorce, "irreconcilable differences".