Justification doctrine thru the centuries
has been taken by theologians
off of Christ twice;
and when that happens,
it is no justification, no salvation, no real Gospel.
This is how that happened:
Real justification based on the imputed righteousness of Christ
was replaced by so-called "double justification" claiming to have
initial justification by the imputed righteousness of Christ
plus second ("final") "justification" based on inherent (actual)
righteousness that then falsely claimed to determine
whether people were saved or not.
Real justification as revealed by Christ in the Scriptural Gospel
is single justification forever valid and never superseded,
a single event that occurs in a moment,
the moment anyone places all their trust for salvation
in Christ alone to be their righteousness,
their Righteous Substitute.
But most people want to trust in their own "righteousness".
So various later theologians added a second "justification"
based on inherent (rather than imputed) righteousness
onto the real justification
to get a so-called "double justification"
(but which is no justification at all
because it is no longer trust in Christ to be Substitute):
people still profess that faith in Christ justifies,
but then try to get "righteous enough"
for "final justification".
Eventually since people are then trusting in
their own "righteousness" anyway,
popular doctrine no longer includes real justification,
namely, that Christ is Substitute,
that he imputes his righteousness,
but rather it retains the added inherent "righteousness",
that is, of people themselves, trying to earn salvation:
that is, by trust in those things that are definitely to be done,
such as, repentance, surrender, commitment, baptism,
church, sacrament, giving, good deeds, endurance
(things that should never be trusted in for salvation
since all trust must be on Christ alone).
Thus "double justification" has been the false theology
that has moved doctrine off of the real justification that
Christ showed and rather onto the false "justification".
That has happened twice:
First, after Paul: by Patristic theologians such as Polycarp
(Epistle of Polycarp to the Philippians, ch 1- 2) and Origen.
Second, in the Reformation: by various non-Lutheran
Reformers such as Calvin (Institutes, vol 3, ch 17, sec 8-10),
Bucer, and Hooker.