The only protestants that come close to following the teachings of Luther about Mary are......well.........LUTHERANS!
The other 60,000 or so sects believe what they feel like believing, the Bible be damned. Every protestant is their own authority on the Bible, just ask.
Only the biblical of Luther's views on Mary were accepted, not the over the top Catholic influence. There was no scriptural warrant for those views so they didn't make the cut to the Book of Concord.
No direct or categorical and stringent proof of the dogma can be brought forward from Scripture.
Tell me again why we should listen to catholics on this????
Your own sources tell us there is NO direct or categorical support for the immaculate conception....yet catholics continue to advance this false teaching.