When I read Adopted for Life (by Russell Moore) a few months ago, I found his discussion of the significance of God's adoption of the Gentiles insightful. At the time, I didn't think much about the unity of Jews and Gentiles specifically, but, rather, I was impressed by the unity that we all share as believers, regardless of whatever natural, physical, and earthly attributes have a tendency to separate us.
Below are excerpts from Moore's chapter entitled "Are They Brothers?"
"As pig-flesh-eating Gentile believers--formerly goddess worshipers and Caesar-magnifiers and all the rest--began confessing Jesus as the Messiah, some Jewish Christians demanded to know, 'Are they circumcised?' This meant of course, 'Are they really part of us? Are they our brothers?' The Gentile believers would respond, 'Yes, with the circumcision made without hands, the circumcision of Christ...'
"This was no peripheral issue. For the apostle Paul, the unity of the church as a household has everything to do with the gospel itself. And where the tribal fracturing of the church is most threatening, Paul lays out a key insight into the church's union with Christ--the Spirit of adoption...
"In his letter to the church at Rome, the apostle Paul raises the issue of adoption....But before he begins his discussion, he addresses the assembled congregation as 'brothers.' (Rom. 8:12) That's a word that's lost its meaning in our churches, I fear. We tend to view it as a mere spiritual metaphor for 'friend' or 'acquaintance...'
"The churches emerging out of Judaism in the first century, however, would have understood precisely how radical this 'brothers' language is. The 'sons of Israel' started out, after all, not as a government entity but as twelve brothers. Everywhere in the Old Testament the people of Israel are defined as 'brothers' as opposed to 'strangers' or 'sojourners...'
"Because we share the Spirit with Jesus, we cry out with him to the same Father (Rom. 8:15, Gal. 4:6). And since what unites us to Jesus is his Spirit, not our flesh, we share a common family with all those who also have this Spirit resting upon them. Since there's one Spirit, there's 'one Lord, one faith, one baptism, one God and Father of all' (Eph. 4:5-6).
"That's adoption. We're part of a brand-new family, a new tribe, with a new story, a new identity."
The unity of all believers in Christ across every other dividing line is a true and beautiful thing; the adoption of the Gentiles into the people of God, and their resultant brotherhood with the Jews certainly teaches us that.
I probably wouldn't have thought any more about the subject, but one of my next books was Bonhoeffer: Pastor, Martyr, Prophet, Spy, by Eric Metaxas (a fascinating and well-written read, which I highly recommend). In Germany in the 1930's, the brotherhood of Jew and Gentile was no safely-assumed spiritual metaphor. Instead, it was a reality for which men were willing to put their reputations, their livelihoods, and possibly their lives on the line. In the early church, it was the Jews who were reluctant to allow the Gentiles in; now it was the Gentiles who wished to kick out the Jews.
"Bonhoeffer went on to say that to 'confess Christ' meant to do so to Jews as well as to Gentiles. He declared it vital for the church to attempt to bring the Messiah of the Jews to the Jewish people who did not yet know him. If Hitler's laws were adopted, this would be impossible. His dramatic and somewhat shocking conclusion was that not only should the church allow Jews to be a part of the church, but that this was precisely what the church was: it was the place where Jews and Germans stand together. 'What is at stake,' he said, 'is by no means the question whether our German members of congregations can still tolerate church fellowship with the Jews. It is rather the task of Christian preaching to say: here is the church, where Jew and German stand together under the Word of God; here is the proof whether a church is still the church or not.'
"Many would have remembered Galatians 3:28, declaring that 'there is neither Jew nor Greek, bond nor free, male nor female, for your are all one in Christ Jesus.' To underscore his point, Bonhoeffer concluded with words from Luther's commentary on Psalm 110:3: 'There is no other rule or test for who is a member of the people of God or the church of Christ than this: where there is a a little band of those who accept this word of the Lord, teach it purely and confess against those who persecute it, and for that reason suffers what is their due.'"
The issue of unity in the church is no small one, for the simple reason that the church is the body of Christ. Woe to the body that is willing to pluck out an eye because it happens to dislike the color! It is Christ who puts together the body, taking disparate elements and knitting them together according to His perfect design. Who are we to say who belongs and who does not?