One of the things which the Diaspora Jewish community is yet to fully comprehend is the strange hybrid religion which is being practiced by millions of intermarried couples and their offspring. There are probably thousands of halachically Jewish kids out there, possibly attending Sunday school or day schools, who also go to church on occasion with a grandparent or father, and see it as completely natural; Jewish kids who are preparing for their bar-mitzvahs, but who have been told by their non-Jewish fathers all about Jesus Christ, and don't understand the contradition; and non-Jewish kids who have been baptised and go to church every week, who believe their Jewish fathers when they tell them that the Messiah hasn't come yet.
In that spirit, prepare for the interfaith festival of... Chrismukkah. An enterprising intermarried couple has institutionalised what is happening anyway in hundreds of thousands of households. And while they insist that "Chrismukkah is a cultural holiday, NOT a blending of religions," it is hard to see how children growing up with such a mish-mash will understand it as anything but; indeed, hundreds of children of intermarriage interviewed for this book have confirmed that that's exactly how they see it.
It's important to realize that when we talk about the development of the Jewish community, the future doesn't hold a smaller core Jewish community with a large number of unaffiliated people who know nothing about Judaism. It holds a smaller core Jewish community with some unaffiliated people and a much larger number of 'Judeo-Christians,' who are practicing a hybrid religion which is unrecognizable to members of either original religion. It is only a matter of time before they outnumber Jews practicing Judaism -- and this is a completely different challenge for the mainstream Jewish community.
PS. Fascinating link on the Chrismukkah website -- www.halfjew.com.