The Angel of Yahweh appeared to Moses in a blazing fire in the midst of a bush. The bush was burning, but it was not consumed. This is probably the same fire that Yahweh appeared as when He made His covenant with Abraham (Gen. 15:13-17).
Elohim has not rejected all of the descendants of Abraham. The people are not rejected simply because they are of the blood of Israel or because they are of Jewish descent.. Paul had just quoted that Elohim had been holding out His arms to a stubborn and obstinate people all day (Romans 10:21). Paul is not coming back now and saying that Jews who reject Messiah are still somehow saved. The point Paul is making is that there are still blood descendants of Abraham that have not rejected Elohim and His Messiah that He sent to Israel. It may seem like they have all rejected Him, but that is not the case.
Paul is now going to use the examples of two of the most revered men of Elohim in the history of Scripture and demonstrate that salvation only came from their faithfulness, not from their works they performed from their own efforts..
Abram was already declared righteous by faithfulness in Gen. 15:6. Why must he now walk blameless before Elohim? Because Abram is demonstrating his faithfulness by walking blameless before Elohim. Israel was told to do the same thing (Deut. 18:13). We are told the same thing (Matt. 5:48).
Without understanding the foundation of Scripture—the Torah—our knowledge of the rest is pointless. The first Book of the Torah, Genesis (Heb. – Bereshith …”in the beginning”), tells us of the origins of all creation including the origins of His people, Israel. Genesis begins with the creation of the heavens and the earth by Elohim and finishes with the death of Joseph.