It is believed that God and Abraham covenanted with each other, thus making Abraham the first ever Jew. In fact, Abraham plays an ancestral role in the holy books of Christianity, Islam and Judaism. As a result of this, all these religions are also known as 'Abrahamic religions'. All three sects believe Abraham to be the father of Israel. Jews and Christians hold this belief due to the birth of Isaac, one of the three patriarchs of the Jewish people.