Judaism is a religion of a nation which lived in the land of Israel in Biblical times. The nation was conquered two times. The first time it was conquered by the Babylonians who destroyed the first holy temple built by King Solomon. The second time it was conquered by Rome, the temple was destroyed, the Jews were exiled until today.
The religion Judaism today exists according to the Law of Moses which was the law of the nation of Israel during this period. Jews are commanded in the Law of Moses not to change the law or the religion. The modern state of Israel is a democracy, which is against Judaism– the law of a theocracy with a King. The hope of the biblical nation of Israel when it was exiled was to return to the land of Israel and to establish the Kingship of King David the Messiah, “return us to you God in repentance, renew our days like the days of old.” There is conflict between modern secular Jews living in Israel and the diaspora and Ultra-Orthodox based on their religious beliefs.