You are right: In Genesis 15: 18-21 God said as you quote. But he also said in Judges 2:21-23, IN THE FUTURE I WILL NOT EVICT ANY OF THE NATIONS THAT JOSHUA LEFT IN THE LAND WHEN HE DIED. Since you know that the Jebusites, who built Jerusalem, and by many historians and scholars are considered the forebears of the Palestinians, were there when God said that, God made it quite clear that Jews cannot claim all of Palestine. It follows that Jews have no legal title to any land outside the borders specifically detailed in UN resolution181, when Israel declared statehood. Israeli violation of UNSC 242, continued occupation of Palestinian territory, is a violation of international law. And, Jewish religious beliefs do not supersede international law. If international law had to conform to the beliefs of Judaism, Christianity, Islam, Buddhism, Hinduism, Taoism, Shintoism etc., there would be no international law.
Law expanding definition of terrorist activity passes first Knesset reading (Haaretz)
from the article: Amr Moussa: Arabs must prepare alternatives to failing peace process