For example, he is perfectly wrong in every way when he writes
The Jews are our open enemies; they do not cease to blaspheme our Lord Christ; they call the Virgin Mary a whore and Christ, the child of a whore. Us they call changelings and abortions, and if they could kill us all, they would gladly do so. And they often do, especially those claiming to be doctors, even if they do help on occasion, for it is the devil who lends his help and seal. They are also practitioners of the medicine used in Italy, where poison is administered to kill someone in an hour, a month, a year, even ten or twenty years. This is the art they have mastered.
Therefore, do not be troubled for them, for they do nothing else among you than to blaspheme our dear Lord Jesus Christ abominably and to seek after our body, life, honor, and property. Yet we want to exercise Christian love toward them and pray for them to convert and receive the Lord, whom they should properly honor more than we do. If anyone refuses to do this, let there be no doubt that he is an incorrigible Jew who will not cease to blaspheme Christ, to suck you dry, and (if he can) to kill you. — Martin Luther
Luther has his good points. But he also has his bad points and those bad points are worse than anyone can imagine.