I think you would agree that whether many or few believe certain thing does not make it true or false. I think that Luther and his collaboratiors in the Reform movement succeeded in forming a theology that generally is accomodating human error, encourages schism, and is in sync with the modern times. This is because of the notions such as salvation through faith alone, anticlericalism, antimonasticism and sola scriptura, and various variants of surety of salvation. These theologies fit the modern man, so whatever scant scriptural support there is for them, the modern man clings to it. This is what makes him what he is.
I agree that it doesn't matter how many people believe something; rather, it is whether the WORD OF GOD teaches it.
As to your understanding of Luther's theology, I do not see it that way at all. A lot of what Luther believed was frankly still quite Catholic. His baptism of infants, for example (which Calvin also held to); and a slight variation on the eucharist (almost semantics but not quite in comparison to say Zwingli's view concerning Lord's Supper) all showed Catholic influence. He also seemed to be quite informed by Augustines views on things in many areas.
Where Luther differed was in what you call the "notion" of salvation by faith alone.
Contrary to your assertion, these theologies do not fit modern man; for modern man's invented religions ALL without exception create a salvation that is at least in some way shape or form dependent upon MAN being good enough in some aspect of life. Luther recognized man as a lowly worm incapable of pleasing God on his own. And, he used Scripture to back it up.
Annalex, I will repeat what I said before. Please pick up the WORD OF GOD itself - exclusive of commentaries by Catholic (or Protestant) theologians. Look at it. Let the Words tell you what they mean. You will not come up with a theology that is too far from Luther's on Salvation.