This is an interesting post. Most of my friends--who are, for the most part amillenialist--love the study of echatology. In one event, my Friend Sean, who is also PCA, recommended that I buy Dr. Kim's treatment of the subject. I, on the other hand, find the subject dry with no vitality to the Christian virtues. However, I don't believe it is unfruitful to the believer's life. Some important men in history have written volumes on the subject; so I guess it isn't too baneful to address this topic. But more particular, I want to focus on the study of Paul's explanation of Romans 9.
In the tradition of the Reformed Presbos, I follow a belief that the church is solemnly defined as "chosen" in the New Testament. Dr. Piper, in his dissertation, wrote at lengths the arguments for the elective tenor of Paul throughout Romans (spec. chaper 9). The ultimate dilemma then is whether Paul's anticipation of complement met--that God's word hasn't failed. Paul wrote in verse 6, "But it is not as though the word of God has failed." But if it hasn't failed, why then are the children of Israel not forthcoming to the salvation made for them? That is explained in the next clause which defines the argument: "For not all who are descended from Israel belong to Israel." Piper then draws the distinction in his book by defining God's promise: Jacob (chosen) and Esau (not chosen). And these two figures in biblical history denote the will of God, i.e. election. And the purpose for the argument is that the purpose of election might stand firm (or be established). If the argument is not sound and, or true, then the word of God fails, and his justification for doing so also fails; and that is the argument Paul is defining, the faithfulness and justice of God by virtue of his word.
In dealing with the nature of justice, Dr. Hodge (Charles) defined all the attributes of God as, "the ultimate foundation of moral obligations in the nature of God." Paul's argument has been stressed upon the nature of God from this point on. The nature of Paul's argument is based on the will of God which encapsulates His justice. And these attributes hang on the justification of Paul's thesis here: that God's word has not failed.
Therefore, God is justified in the justification of his people ("Israel") by virtue of election, and as a result, his word still stands. The thesis is not volitile to the nation of Israel, namely because his promises still stand, albeit for the "true" nation of Israel, the Church.