This is a section that shows that the unification of Jew and Gentile is clearly and unmistakably the work of the Christ. In bringing these two groups together in the Body of Christ (Kingdom) Jesus has done something that would have been considered so improbable that it can only be the work of God. To make matters more interesting, Paul cites Isaiah 11 in this section as being fulfilled in this unity within His Body.
7-11: Paul admonishes the two groups to accept one another as Christ has accepted them, in other words Jews and Gentiles should accept one another as Jesus has accepted each group; a group of sinners. In doing this, Jesus who became a servant to the Jews, has kept His promise to the patriarchs so that the Gentiles may glorify God by joining in relationship with God, rather than to continue in rebellion against Him. Paul then goes on to cite several Old Testament passages that confirm this statement. (Rom. 15:9 cf. 2 Sam. 22:50; Ps. 18:49; Rom. 15:10 cf. Deut. 32:43; Rom. 15:11 cf. Ps. 117:1;) Note that these quoted verses are spoken of as present reality and not something in the distant future.
12: In this verse, Paul quotes Isaiah 11:10 from the Septuagint, which is an ancient translation of the Hebrew Old Testament into Greek, as was his custom. Again, this verse is quoted within the context of vv. 7-9 as present reality. I point this out because from time to time people assume that the prophecy of Isaiah 11 must refer to some future date, since lions and lambs don’t usually hang out together these days. However it is vital to understand that prophecy is generally understood as not being literal in fulfillment. In this case, the predators and their prey referred to by Isaiah are about as likely to live in peace as Jews and Gentiles… and Jews and Gentiles are a whole lot more important! For God to accomplish unity in the Body of Christ between Jew and Gentile is every bit as miraculous and theologically speaking much more significant than peace in the animal kingdom.
13: Here, Paul winds up with a prayer for joy and peace amongst God’s people who trust Him, that they may be filled with hope. Considering what we have just seen in these two passages, I would say that if we cannot find hope and trust in God here, then we are woefully weak in understanding. Unity on this earth, in this life between these two devoted and committed enemies of the ancient world may not seem like such a big deal to us… but that is only because of the magnitude of the miracle that God has performed through the sacrifice of Jesus on the cross.
As we consider this Christmas, and all that it means to us and our celebration of the coming of Jesus Christ, the more we look, the more we consider and the more we ponder… the more awesome and amazing the Incarnation becomes, for it truly changed everything. In spite of the best efforts of sinful Man, God has done the “impossible” in more ways than we usually even begin to consider. Beginning with a miraculous birth, God has accomplished so many more miracles through the life, death, burial and resurrection of Jesus Christ, that it may even seem that the miraculous birth was no big deal, for if God can take away sin, redeem Mankind and unite Jew and Gentile in the Body of Christ, then what is there that God cannot do?