Nittel Nacht
"The Talmud, with its share of rabbinic repudiations against Jesus, was never a big fan of Christmas. Call it the Grinch. Indeed, the rabbis looked at it as a day of mourning—perhaps due to the suffering that Jews encountered in Jesus' name throughout history. And Christmas Eve—named "Nittel Nacht" by Jewish scholars in the 17th century—took on a life of its own. Some Jewish mystics were under the impression that many apostates were conceived on Christmas Eve (which is one reason the rabbis forbade sex on Dec. 24; more on that later). In Europe, the Jewish community was victim of more acts of violence on this night. All in all, it didn't end up being a festive evening for Jews.
And so the rabbis decreed that the public study hall be closed and that no Torah learning take place on this night. I guess it's our version of "Silent Night"—literally. The edict came about partially because of pogroms, but the leaders were also concerned about the popularly held belief in Judaism that studying the Torah brings spiritual benefit to the world at large. Many didn't want to make this positive contribution on what they considered a "pagan" night.
Although there is no exact demarcation as to the genesis of this odd holiday, the renowned Talmudist Rabbi Samuel Eides (commonly known as the Mahrasha in Torah circles) observed Nittel Nacht as early as the late 1500s. The Baal Shem Tov, a famous Jewish mystic and the founder of Hasidism, popularized the holiday in the 1700s. Many rabbis after him added on their own special rules. By the mid-1900s, when Judeo-Christian relations matured, the Christmas Eve customs fell mostly by the wayside as the Jewish community wanted to show their support for their Christian neighbors..."
