Do you have a source for that? I had understood that the opposite was true-- that Luther originally called for tolerance of the Jews, hoping to convert them, and became violently antisemitic later in his life.
I need to clarify my earlier posts after checking into this matter more thoroughly. What I recalled was someone citing Luther's last sermon. Since I had recalled a conciliatory citation, I framed it as "repenting."
Luther indeed was conciliatory in his final statement about the Jews; but it was not an attitude of repentance re: his booklet, "The Jews and Their Lies." Luther did not take on the Jews until very late in life. Let me quote from a messianic online article (http://jesus-messiah.com) :
"Martin Luther was an avid supporter of Jews nearly all of his life until in the last few months of his life he was shown a Talmud with all of its blasphemy against Jesus and Christians. This fueled his indignation and he wrote his famous diatribe *The Lies Of The Jews.* His writing would not have been rebuked had he not gone beyond the Christian conduct and advocated violence toward Jews. But Luther had done this already against the poor peasants in the Peasant War and the Jews said nothing!"
You have to understand that Luther wrote diatribes vs. a lot of folks. It was his style. It was also characteristic of medieval times for folks to be brutally raw. Luther was certainly bombastic across the board. Some scholars distinguish what Luther said in this short (months) period of time as "religiously anti-Jewish, though not racially anti-Semitic." Source: Associated Press, 6/8/03
The bottom line of my previous post is that I was going on recollection of what Martin Luther said in his absolute final sermon:
Protestants should emphasize Luther's final word on the subject: "We want to treat them with Christian love and to pray for them, so that they might become converted and would receive the Lord" (Weimar edition, Vol. 51, p. 195). {this citation can be found as part of a Lutheran Church-Missouri Synod resolution under FAQ @ the LCMS web site).
Luther's final word, which is to love and pray for the Jews, is rarely if ever quoted by those who would only quote the negative things Luther wrote about them. I think folks should tell the whole story.