It's an image that has become the iconic expression of ignorant anti-semitism. We consider that a person who "still thinks Jews have horns" is a person who lives in such an isolated, ignorant world that they have never met a Jewish person.
It's an anti-semitic image that has been around for a very long time. But where did it come from?
Amazingly enough, this negative image that has plagued Jews for centuries is rooted in bad translation!
וְרָאוּ בְנֵי-יִשְׂרָאֵל, אֶת-פְּנֵי מֹשֶׁה, כִּי קָרַן, עוֹר פְּנֵי מֹשֶׁה
The key is the word קרן / karan. The correct translation is the past tense verb, "shone" . . . but at some point along the way, someone mis-translated the word as the noun "keren" meaning "horn." Hence, Moses . . . and by association, Jews . . . have horns.
But Moses' face was infused with light from his proximity with God during the revelation of the Torah. This imagery is one of our most elevating legacies from Moses . . . we, too, can be infused with light in the presence of God and in our engagement with Torah.
So, we may not have horns . . . but we do have light!