As a Messianic Jewish minister, I have many discussions in December about religious holidays.
Messianic Judaism does not celebrate Christmas (we have Sukkot to commemorate the Messiah's birth) but teaches that Christians can celebrate that holiday appropriately . Also, Judaism must deal with similar issues about pagan influences in Purim customs.
Today a friend sent me a link to a talk about the pagan roots of Christmas, presented by Rabbi Lawrence Keleman. If you take the time to contrast this talk with the Christmas essay linked above you will see how the talk confused the official stances of religious leaders with the overly revelrous practices of laypeople. For example, it mentions how Christmas was outlawed in much of Puritan New England. But when discussing this bit of history it implies that excess in Christmas revelry was accepted, not fought, by by church leaders in England.
Every religion has such issues. But just because laypeople acted irresponsibly in the name of religion does not mean their religious leaders approved.
I earlier mentioned Purim: most American Jews today are ignorant of how their European ancestors filled that holiday with pagan customs, and would be embarassed if they found out. It is a bit ironic that Yochanan's account of Yeshua's teachings this time of year (during Chanukah) begin with a warning not to throw the first stone.
UPDATE: This article had some information about the history of Christmas trees that was new to me.
