Yes, I know that many Lutherans, including Luther himself, taught that. But – as I never tire of repeating – Lutheran doctrine is not decided by asking what many Lutherans, or Luther himself, believes or believed. If you want to know Lutheran doctrine, or the doctrine of a given Lutheran Church, the place to go is the confessions.
The basic confessions are the
Apostles’ Creed, the
Nicene Creed, the
Athanasian Creed,
Confessio Augustana, and
Luther’s Small Catechism. Some Lutheran Churches, such as the LCMS, also hold to some other confessions (basically the rest of the
Book of Concord), but they are not binding in the same way, and most European Lutheran Churches rejected them – especially the
Formula of Concord.
The basic confessions – especially
Confessio Augustana – do put emphasis on justification through faith, but you will not find in them the kind of emphasis that Indifferently insists on for ‘genuine Lutheranism.’
And as you see
here and
here, Indifferently doesn’t really know what Lutherans actually teach on justification, as he claims that we teach the calvinistic doctrine of imputed righteousness. The difference is basically that while
Calvinists teach that the righteousness of Christ is imputed to us, and that faith is not,
Lutherans teach that faith itself is imputed or reckoned for righteousness, following St. Paul: “And to one who does not work but trusts him who justifies the ungodly, his faith is reckoned [imputed] for righteousness.” (Rom 4:5) That basically means that Lutherans see faith as sufficient. But the faith in question is not any old faith, but an
active faith, following St. Paul’s point, that the faith which “is of any avail” is “faith working through love” (Gal 5:6). That itself doesn’t necessarily mean that one must act — that would rule out people who cannot act — but it states that you also need love to be saved, the love of God “poured into our hearts through the Holy Spirit” (Rom 5:5, cf. vv.1-11). This love must be lived out according to each person’s ability.