It was in Douglas Moo's commentary on Romans that I first learned about Paul's use of the indicative and the imperative moods.
Indicative: "expressing a simple statement of fact, rather than something imagined, wished, or commanded."
Imperative: "denoting the mood of a verb that expresses a command or exhortation."
(both definitions from the Compact OED)
Paul's imperatives (his commands or exhortations) are always based on an indicative (his statements of fact). In other words, Paul will say something like this:
The dividing wall of hostility has been broken down. You are one in Christ. That's the indicative statement.
Therefore, make every effort to preserve this unity of the Spirit in the bond of peace. That's the imperative statement.
In the epistle to the Ephesians, chapter 2 through 3:13 is essentially indicative, while chapter 4 is essentially imperative. Chapter two "indicates" a reality about being "in Christ," while chapter 4 exhorts the Ephesians to live accordingly. Do you see how Paul's imperatives hinge upon the reality and truth of his indicatives? If there is no truth in his indicative statements, then there can be no grounds for his imperatives. On the other hand, if his indicatives are true, his impassioned imperatives are all the more worthy to be heeded.
Now, chapter 2 of Ephesians emphasizes the unity of Jew and Gentile in Christ. The "dividing wall of hostility" has been broken down. Jesus Christ, Paul says, preached peace to those who were far off (the Gentiles) and peace to those who were near (the Jews). As a result, both groups are now in Christ, and in Him are being built together, joined into a holy structure that is intended to be the eternal dwelling place of God.
This is the essence of the "mystery" that Paul goes on the delineate in the first 13 verses of chapter 3. Then, in Chapter 4 Paul exhorts the Ephesians to live in accordance with this calling to unity that they have all received. Given that call to unity, bickering and strife undermines the very call of God in our lives, not only as individuals, but as a people. Therefore Paul advises, "Be completely humble and gentle; be patient, bearing with one another in love. Make every effort to keep the unity of the Spirit through the bond of peace."
Now if the cross of Christ has removed the dividing wall between Jew and Gentile, bringing reconciliation and one-ness, has it not also removed the many dividing walls that continue to exist today between Christian and Christian? I am not speaking here of denominational conflict. I am speaking of a more personal level of conflict. Conflict between Christians (that is, between people who are "in Christ"). Even conflict in Christian marriages, for example.
In the world that Paul knew, conflict between Jew and Gentile was so deep-seated and pervasive, so "expected," that to speak of peace between them, to speak of Jew and Gentile in unity, was to speak of something deeply mysterious. Only God could work such a thing, and through the cross of Christ God
did work such a thing.
His purpose was to create in Himself one new man out of the two, thus making peace, and in the one body [that is the collective "body" that is the people of God] to reconcile both of them to God through the cross, by which he put to death their hostility.
God put to death the longstanding historical hostility between Jew and Gentile through the cross of Christ. This being so, has He not also put to death, through the cross, all other forms of hostility that spring up among us who call ourselves Christians, children of God?
"Be completely humble and gentle; be patient, bearing with one another in love. Make every effort to keep the unity of Spirit through the bond of peace."
When we strike at one another, when we insult and demean one another, when we curse and thrash among ourselves, seeking advantage, we have grieved the Holy Spirit, whose bond is a bond of peace.
What about Christian marriages? These passages in Ephesians don't explicitly apply to marriage (in chapter 5 he'll get to that), but surely the unity of the Spirit in the bond of peace must apply to Christian couples as well as to Christians generally. Let me quote the final verses of chapter 4 as if they were addressed, say, to husbands:
Do not let any unwholesome talk come out of your mouths, but only what is helpful for building up your wife according to her needs....
Now, just for good measure, let's imagine that Paul's exhortation is addressed to wives:
Do not let any unwholesome talk come out of your mouths, but only what is helpful for building up your husband according to his needs....
This is not merely ethical exhortation. This is preserving the bond of peace that is a fruit of the Holy Spirit. This is, in other words, a way of honoring your God.
And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption. Get rid of all bitterness, rage and anger, brawling and slander, along with every form of malice. Be kind and compassionate to one another, forgiving each other, just as Christ forgave you. Ephesians 4:29-32
Paul says in Ephesians 4:18 that when our hearts are hard our minds are darkened. We become, in other words, unteachable. We do not learn. And so we sink deeper into old enmities and strife. So it is that we have often failed, as the people of God, to preserve, on the personal level, the unity of the Spirit in the bond of peace. The Spirit, I am sure, is grieved by the hardness of our hearts. "I will put a new heart in you, a heart of flesh in place of a heart of stone," says the Lord God, but how often have we, with pious and high-sounding rationales, rejected His merciful offer?