The name ‘Lutheran’ is a bit like the name ‘Cheesehead’ is to Packers fans. It was made up by Bears fans to make fun of Wisconsinites, but the name was endearing so it stuck.
Well, the title ‘Lutheran’ was likewise made up by Roman Catholics as a derogatory term. It was common to name heresies after their heresiarch: Arians after Arius, Marcionism after Marcion, Apollonarism after Apollinaris, etc. They thought if they pinned the Evangelical movement on one person, Luther, that the “bad PR” would scare people away from it. But the thing is, it was never just Luther. It was always a movement. It started in the Augustinian Order, and moved outward to much of Germany, resonating with both nobles and commoners. That movement subscribed to several
Confessions of belief. It is these Confessions that make one ‘Lutheran.’
Luther himself never wanted anything named after him. He said, “What is Luther? A man, a stinking bag of maggots!” He preferred that Lutherans call themselves ‘Evangelical Catholics,’ and that’s how I see myself. Not as following Luther or any man, but as following Christ in the continuing [Evangelical] Catholic Church, and claiming all the patrimony that came in the first 1500 years of Christianity, too. In other words, Lutherans view themselves as the truest Catholic Church, even if Rome got the house in the divorce. They consider Rome part of that church, even if they believe it to have some errors. So are the Orthodox Churches, and even “Protestant” churches.