Complex sentence: Christianity and antisemitism deals with the hostility of Christian Churches, groups and by Christians in general to Judaism and the Jewish people, which developed from the early years of Christianity and was reinforced over the ensuing centuries, and culminated in the Holocaust.
Split into simpler sentences: Christianity and antisemitism deals with the hostility of Christian Churches, groups and by Christians in general to Judaism and the Jewish people. Christian antisemitism developed in the early years of Christianity and was reinforced over the ensuing centuries, and culminated in the Holocaust.