Yes it is. Abraham is considered the 'father' of the Jewish people and was from a city called 'Ur' in Mesopotamia, which is now in modern Iraq. The Bible (book of Genesis, also part of the Jewish scriptures) describes how God came to Abraham and said that he (Abraham) and his descendants would be a great people and he would give them their own land, and that through this people, God would reveal himself and his 'salvation' to all mankind. Genesis then tells the story of Abraham travelling through the Middle East towards Palestine, and how ultimately one of his descendants, Moses, leads these people (who became known as the 'Hebrews') from Egypt to the edge of Palestine (this is the 'Exodus'). Moses died before entereing the land, but the Hebrews did enter and occupy the land that became known as Israel. Thus the first part of God's promise was fulfilled - to give Abraham and his descendants a land of their own. This remains the crux of the modern Jewish claim to the territory of Israel. However, religious Jews still hope for fulfilment of the second part of God's promise (called a covenant) to Abraham to reveal himself to all mankind and to provide salvation to all mankind through the Hebrew people - they await 'the Messiah', and every year at Passover they look for the coming of this Messiah. The Christians believe that God's promise has already been fulfilled and that Jesus is this promised Messiah (in fact 'Christ' means 'Messiah', it's just the Greek equivalent of the Hebrew). Jews who become Christians accept that Jesus was and is their expected Messiah who came from Abraham's descendants to reveal God to mankind and provide a means of salvation (forgiveness of our rebellion against God and a means to be reunited with him both spiritually and eternally in heaven). So, both Jews and Christians in a sense claim 'Abraham' as their father from Ur in Mesopotamia, now Iraq!