I need to explore this more, but I think I've come upon another very devastating argument against the Protestant understanding of Justification. Protestants have been very adamant that the term "Justify" (dikaioo in Greek) means "to declare righteous," specifically in a legal context, and have pointed to various passages to support their claim. But it seems as if one passage that I'd expect them to appeal to - Romans 3:4 - has been routinely neglected, and I can only think of one explanation for it.
In this verse we read: "Let God be true though every man be false, as it is written, 'That thou mayest be justified in thy words, and prevail when thou art judged.'" Here Paul is quoting Psalm 51:4, which happens to use the term dikaioo, and which also seems to be in a forensic context (since the word "judged" appears here). You would think Protestants would be all over this, but I don't recall them appealing to this text (favoring other proof texts instead), and I think I know why. Looking closely, you notice that the term dikaioo here is speaking of God Himself being justified, which means this obviously cannot mean "declare righteous"! The only option then is that dikaioo, in this ever so important junction in the Book of Romans, must mean something akin to "vindicate," just as Protestants claim James 2 must be using dikaioo to mean "vindicate". If this holds up, this is very bad news for Protestant exegesis, because Romans 3:4 would thus dictate how we read dikaioo in the context of Romans 2-4. And if Paul is speaking about "vindication" in these chapters, then there goes the Protestant understanding of justification up in smoke.