Who was the first real Jew by birth?

Isaac was the first real Jew by birth. Although Abraham is considered the father of the Jewish race because of his call and covenant promises, his blood remained genetically Syrian. The context identifies Isaac as the first son of promise, making him the first real Jew by birth.

Les explains that the Jewish nation was not yet on the scene. Abraham was a Syrian; his two brothers were Syrians up in Syria and Haran, and his blood did not change when he received the call and covenant promises. Scripture therefore considers Abraham the father of the Jewish race, and people call him the first Jew, but genetically Isaac would be the first son of promise and the first real Jew by birth. Abraham came out of Ur of the Chaldees and then into the land of promise. Paul uses Abraham as an ideal example of a man who was justified.

Who was the first real Jew by birth, Abraham or Isaac?

Isaac was the first real Jew by birth. Abraham is regarded as the father of the Jewish race because of his call and covenant promises, but his bloodline remained Syrian. Isaac, the son of promise, is therefore identified as the first actual Jew by physical birth.