Why does Paul quote the Old Testament so much in Romans 9?
Paul quotes the Old Testament in Romans 9 because he is dealing with Israel's past, and Israel's dilemma had been prophesied. God knew Israel would be blind and would not recognize her Messiah when He came, so Paul appeals to old prophecies such as Hosea to show this.
Les explains that in Romans 9 Paul is still dealing with Israel's past, so it is only natural that he would dip back into the Old Testament. Israel's dilemma had been prophesied: God knew Israel would be blind and would not recognize her Messiah even when He came. Paul therefore cites the old prophecy of Hosea in verse 25, where God says, "I will call them my people, who were not my people, and her beloved, who was not beloved." This shows that Israel's condition and God's dealings were already foretold in Scripture.
As he saith also in Osee, I will call them my people, which were not my people; and her beloved, which was not beloved.
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