Luther started out with "that christ was born a jew" where he argued we should remove restrictions on jews and let them live in our midsts freely, as they were not allowed in trade, or any authority position, not allowed to live in the cities, had to wear identifying clothes and more (as it was for most of the Christian rule), so that they may see the prospering christian ways and convert.
20 years later he wrote "on the jews and their lies" where he argues we should burn down the houses and synagogues of jews and kick them out from our lands to protect the general well being of the public

This seems to be a sort of microcosm as Christians sometimes forget the reason the restrictions were put on them and try to show mercy and help them from their wickedness, just as Luther did. Then they quickly realize the reasons for their persecution again and every bit of compassion is gone all of a sudden.