Why did Israel fail to recognize the Messiah?
Israel's failure to recognize the Messiah was prophesied; God knew the nation would be blind to these things and would not recognize her Messiah even when He came. Paul connects this to Hosea's prophecy about those who were not a people becoming God's people.
Les explains that Paul is dealing with Israel's past in Romans 9, and he dips into the Old Testament because Israel's dilemma was prophesied. God knew Israel would be blind to these things and would not recognize her Messiah even when He came. Paul then references Hosea's prophecy in verse 25: "I will call them my people, who were not my people, and her beloved, who was not beloved." This fits God's broader plan: Israel's covenant promises are yet going to be fulfilled, but not until God is through dealing with the Gentile church.