In the interesting Briefing focussing on singing in church, Gordon Cheng cited the myth that Martin Luther appropriated drinking songs for Christian hymns. As far as can be known, Luther once used a secular tune for his hymn "From Heaven Above to Earth I Come" but later rejected it because of its worldly associations. But the origin of this very popular and persistent notion seems to be based on a misunderstanding of the musical form known as the "bar tune." Many Lutheran chorales are in the form AAB, which is called "bar form." It has nothing to do with taverns, but means the song has two sections using the same musical phrase, ending with a second tune. Richard Lammert, Concordia Theological Seminary librarian explains this in his article Did Luther Use A Drinking Song as the Basis for A Mighty Fortress is our God?
If anyone knows a way of dispelling this myth forever, do it, do it, do it!