The Abrahamic religions are those that can trace their history back to Abraham. Many believe that the three Abrahamic religions worship the same God. Judaism, the first Abrahamic religion, is considered to be an ethnic religion because it was the indigenous religion of the Hebrew people, but Christianity and Islam are considered to be universalizing religions.
The significance of Abraham in Judaism and Christianity begins in Genesis 12:2, when God says to Abraham "I will make of you a great nation." According to Jews and Christians, this promise was fulfilled as Abraham's son Isaac was the father of Jacob, who founded Israel.
According to Islam, the significance of Abraham's lineage was through his eldest son, Ishmael. Muslims believe that Mohammed is a descendant of Abraham through this line. Muslims also believe that Abraham was the first Muslim.