How do negotiate with people who believe that Palestine is their land because God gave it to them three and a half thousand years ago?

Let's say, just for the sake of the argument, that they were given that land by divine decree, as they claim. That very same G*d who, according to them and according to their holy books, gave them that land, also took it away from them in punishment for their misdeeds there, and he forbade them to try to take it back by force. In fact, according to their holy books, he forbade them to try take it back under any circumstances.