What nationality was Abraham originally?
Abraham was originally a Syrian, not a Jew. He came out of Ur of the Chaldeans, and though he later became the father of the Jewish people, his original nationality was Syrian; Sarai was also Syrian. This distinction matters because God chose him out of that one race to begin a new people through whom redemption would come.
Les explains that Abraham came on the scene at about 2,000 B.C., after the first 2,000 years of human history covered in Genesis 1–11. Out of the one race of Adam, God picked one man down in Ur of the Chaldeans. Les notes that people are often surprised when told Abraham was a Syrian, because they assume he was a Jew. He did become the father of the Jewish people, but originally he was a Syrian, and so was Sarai. From Ur, he migrated into northern Syria. God promised Abraham that out of him He would bring about a nation totally different from any other race, through whom God would communicate and bring the plan of redemption to the whole human race through Israel. God also gave Abraham the Abrahamic covenant, promising to make of him a great nation, put him in a geographical area of land, and one day come to be their king and government.