Paul is speaking about Jew and Gentile—two different ways of life—being brought together under the auspices of the work of reconciliation Jesus Christ Himself did. God and Christ began the process of reconciliation through Christ's sacrifice. They actually laid the groundwork a long time before that, but Christ's sacrifice got the ball rolling for the whole process.
That sacrifice destroyed the enmity between God and man. It also destroyed the wall, division, or partition that separated men from other men. In Ephesians 2, Paul focuses on the division between Jew and Gentile, but it could also be black and white, man and woman, or slave and free. It could be whatever separates one person from another. Christ's sacrifice did the work to break down all those walls. Once we accept the sacrifice of Jesus Christ, those human divisions—those demographics—mean nothing spiritually.
Our demographic is now "Christian," follower of Christ, and the way of life that we live is Christian. It is not Jewish, not Gentile, not male, not female, not black, not white. Our life is Christ's life. Our identification is as His disciples or as God's children or His elect. So, those physical differences between us should fade into the background. They should fade away for all time once the resurrection comes—because we will then be fully spiritual brothers and sisters in Christ, all part of the same God Family. The way Paul phrases it in Ephesians 2:21-22 is that we are now part of the same building—"a dwelling place of God in the Spirit." God wants to live in us. We are now being built into one Temple, each of us a brick in its wall, so to speak.
We are now all one Body. We are all cells in that one Body, that is, Jesus Christ's Body. Paul writes in Ephesians 4:4, "There is one body." If there are disagreements between the cells of that one Body, then the Body is in danger of becoming divided. But the Body cannot be divided because it is one Body.
That is why reconciliation between brethren is so essential! If reconciliation does not occur, then something will happen in that Body—and it is not good. One or the other, or both, will be ejected from the Body if it does not get resolved—because the Body cannot function properly with internal strife. The Body must grow together into unity! The middle section of Ephesians 4 speaks to this: "The whole body, joined and knit together by what every joint supplies . . ." (verse 16).
Thus, there cannot be schisms between true members of the true church. This is why it is so vital for brethren to be reconciled to one another: because it is crucial to the growth of the church that we learn to get along and to put these "things that offend" behind us.
Perhaps now these often-read verses will have more meaning:
John 15:11-13 "These things I have spoken to you, that My joy may remain in you, and that your joy may be full. This is My commandment, that you love one another as I have loved you. Greater love has no one that this, than to lay down one's life for his friends."
John 15:17 "These things I command you, that you love one another."
