These LCMS Theses on Justification (PDF) succinctly distinguish objective justification from subjective justification and give the sedes doctrinae for the good news that God absolved the world by the work of his Son:
That is the position of the Lutheran confessions (Ap IV, 103-105; FC SD III, 57), not a later development.
Some argue against objective justification by starting with the premise that justification is either objective or subjective, finding proof that Scripture teaches a subjective justification, and concluding that objective justification is not taught in Scripture. One could as cogently start with the premise that reconciliation between God in Christ and the world is either objective or subjective, find proof that Scripture teaches a subjective reconciliation, and conclude that objective reconciliation is not taught in Scripture.
That the premise is false is clear from 2 Cor. 5:19-20, where Paul immediately follows his announcement that the world has already been [objectively] reconciled with God with an exhortation to be [subjectively] reconciled with God. On the relationship of reconciliation with justification or the forgiveness of sins, see Objective justification: God in Christ reconciled the world, not imputing their sins against them (PDF).