Over at IGN, Roy Schwartz wrote a pretty good article about the resemblances between the character "The Thing" in Fantastic Four and the guy who designed and drew him, Jack Kirby. Almost all the heroes Jack created or co-created, including even some villains, have a certain amount of Kirby in them. Some, like Ben Grimm (aka The Thing), Nick Fury and just about any protagonist in Jack's Fourth World, are more obvious than others but there was a lot of autobiography in there. And like I'm quoted in the article saying, I often re-read a Kirby comic I've read a zillion times and suddenly spot a dose of self-reference in it I'd never spotted before.
The article contains a reproduction of a Hanukkah card that historians cite to prove that in Jack's mind, The Thing was and is Jewish. I suspect Jack must have said that in some interview once, as well. But some people don't know the history of the card. They think it's something the Kirbys designed and printed up to send to all their friends. Or something Jack issued to declare the character's faith to the world.
Nope. There was only card like this and it was sent to a good friend of the Kirby family, David Folkman. What happened was that David sent a Hanukkah card to the Kirbys and they — Jack and Roz — decided to reciprocate. Roz bought a printed Hanukkah card in a store and Jack added the drawing. I don't think Jack intended it as a public declaration of Ben Grimm's religion. It was just something they sent to Dave Folkman who later shared it with the world.