Having been married into an orthodox Jewish family for 15 years (1972-1987), my educated guess is that the orthodox nephew will feel left out regardless, unless you all take up celebrating Hannukah, which actually doesn't usually overlap with Christmas; this year it started December 8 or 9, as I remember, and next year I think it comes even earlier. Anything you create will be outside of his tradition, which, if he is truly observant, is what really matters to him and has meaning for him. Anything that smacks of Christianity or Christian traditions will remind him that his people (read, his relatives, his family members, his parents' parents) have been hated, burned at the stake, accused of every conceivable kind of crazy horrors, generally persecuted, down through repetitive centuries. The fact that Dec 25 is a national holiday not only in the US but all over Europe just reminds him of how insecure and unsafe is his place in the world, outside of Israel or a few tight communities scattered across the world. He has a strong, rich, long and deep tradition of holidays and observances which have sustained and comforted Jews through the worst and hardest of times, and he no doubt believes that his are God's chosen people (the question is sometimes "chosen for what?", but that's a different thread altogether). What to do about holidays is something I struggle with pretty much every December, because I have an orthodox daughter and grandson, a non-believing son, and a husband who just likes to put up lights and a tree, and whose birthday is 12/26. I'm always ambivalent no matter what I do.