When we exercise God-given faith in Jesus Christ, we are "justified", which means "declared righteous" by God, as though we had never sinned.
We need to remember that Justification is COMPLETE upon the exercise of God-given faith. It's complete because the New Covenant is a UNILATERAL covenant in the sense that God did it all. He fulfilled the New Covenant completely because, as the Old Covenant proved, man will always fail (AKA sin), and therefore never be able to attain his own righteousness.
But because we born-again Christians are completely "justified" by faith, don't be fooled by some who use the term "Justification", but mix this Gracious truth with Legalistic requirements. Grace plus Law for salvation is not Grace at all (Rom. 11:6).
The neo-legalist “New Perspective” folks SAY they believe in biblical Justification, but then spin it to be a FUTURE Justification dependent on a proper walk with Jesus as Lord, thereby fulfilling THEIR side of a covenant.
This is pure Legalism, disguised as grace by citing the SOURCE of the meritorious walk as God, and then saying it’s not meritorious. Like a Roman Catholic teacher calling their rituals “grace”, while still saying they “merit” heaven.
You can wade through 5,000 pages of N.T. Wright (Anglican Bishop of Durham, and leading "New Perspective" teacher), and attempt to wrap your brain around his prolific explanations of Second Temple Judaism, but it all boils down to that ancient error of “works” salvation, and a convoluting of the "simplicity which is in Christ."
Subtle, like all the “best” heresies.