The Palestinian Mandate is a nice term for "Great Britain is holding this land by force." GB had no right to the land. Israel is founded on land held by a foreign occupying force. The Arab states not agreeing to accept the legitimacy of that foreign occupying force does not make that occupation legitimate.

Jews should be able to live in peace and practice their religion everywhere. As they did in Palestine until the early 20th century. The problems started when outside powers decided to start ethnically cleansing Palestine to make it a Jewish-only state.