Ezekiel is told to unite two sticks, symbolically according to Radak, or miraculously according to Rashi and Radak's father. On one of those he wrote "Judah and the Children of Israel who are his friends," and on the other "Joseph, the House of Ephraim, and the Children of Israel who are his friends." This is meant to predict the future reunification of the Northern Kingdom with the Southern, which will apparently precede God's taking the exiles back to their land, where they can be made into one nation, with one king.
Note that the verse speaks of the two sides as Judah and Ephraim and their respective cohorts. The origins of their split, in the Book of Kings, might suggest that they had a dispute over one question, whether to submit to Rehoboam's (Solomon's son) taxation, but Ezekiel is seeing them as two kingdoms that differ in basic outlook.
Recognizing that Ephraim and Judah were at conceptual odds with each other explains also why the Prophets often refer to the Northern Kingdom as Ephraim—it was their perspective that typified the Kingdom. The challenge of reunification, then, is to bring together those who disagree, even violently, into a productive working relationship.
Unifying Despite Our Differences
Some of us might think that can only occur when all Jews happen to already agree, but I do not believe that was Ezekiel's intent. If he meant that, it seems to me, he'd have written the two names on one stick; his writing them on two and then bringing them together suggests they will maintain their separate identities. In spite of that, he is holding out the hope that they will still manage to reconnect.
Isaiah's vision of the angels (read in a different haftarah and which forms the center of the "Kedushah" prayer in synagogue), suggests a similar idea. He describes them as calling out to each other, and then saying, "Holy, holy, holy is the Lord God." That calling out, at least in Rashi's reading, is to make sure they recite the "Holy, holy" together. Each angel has its own task, Jewish tradition claims, but their highest expression is when they praise God as one. Here, too, Ezekiel is telling us that our task is to find a way to unite while also maintaining our independent status and views.
I do not believe that means becoming indifferent to others' views or lifestyles, to confuse a desire for unity with an apathy to right and wrong. Accepting others' differences can only occur within the range of the morally plausible. Allowing others to act immorally fosters anarchy, not unity.
Unity comes once we have established parameters of accepted behavior; within those, the range offers opportunities for different people to focus on and emphasize their particular interests and concerns. Many of the differences between Ephraim and Judah are fixed and unchangeable. What can be adjusted is the two camps' inability to work together. They can, with effort, build a polity that knows when and how to compromise.
The Key to Redemption, in Joseph's Time and Beyond
That view of unification makes clear how it could lead to the benefits described here-- return to Israel, active and open presence of God in our midst, rebuilding of the Temple, and the return of a Davidic king. Unity is the required first step, because none of those was meant to be externally imposed.
Rather, Ezekiel is telling us that they ideally come in an environment that lets them flourish. Once we know how to reject what is absolutely wrong, make universal what is absolutely right, and grant people the opportunity to differ reasonably on the rest, we will be on the road to the final redemption.
This idea also shows us how the haftarah relates to the Torah reading. Joseph reveals himself to the brothers at the point that Judah has made clear at least his awareness that Jacob cares more about Benjamin than about him, Judah. Judah knows that returning without Benjamin will kill the old man, but that the loss of Judah himself would not be as catastrophic. Whatever we think of Jacob's parenting skills, Judah's ability to recognize and accept the different feelings his father has for him and his brother led, in their case, to the outcome they all wanted, reunification.
One Famous Verse, Two Important Ramifications
R. Joseph Albo, in his fifteenth century work on Jewish faith called Sefer Ha'Ikkarim, the Book of Principles, insists that God's promise to make the Jews one nation, in verse 22, was originally meant to apply during the Second Temple; it was only when that failed that it was left for Messianic times.
In context, it helps him make a fascinating point, that some prophecies meant for earlier times were postponed by human failure to actualize them. That also means that nothing miraculous is needed to achieve at least that aspect of Messianic times, since it could have occurred in the Second Temple era, had we only acted properly. We need not wait for it, as we wait for the Arrival, we need only make it happen.
The second example highlights some of the issues we've been discussing. R. Solomon Kluger, in his book of Responsa, HaElef L’Cha Shlomo, A Thousand For You, Solomon, deals with a questioner who did not wish to say the morning blessing "shelo asani goy," "who has not made me a non-Jew." The questioner noted that Jews are also called "goy," "nation," as in our verse, which refers to us as a "goy echad ba’aretz," "a unified nation in the Land." R. Kluger answered that Jews are only called "nation" in the aggregate; the morning blessing refers to a non-Jewish individual that way.
He seems to understand the blessing as thanking God for not making us like non-Jews, who are, each of them on their own, a complete whole. Jews, on the other hand, are only a complete whole in unification with others. That he could see the blessing as thanking God each morning for being incomplete, for needing other Jews to be a complete whole, strikes me as a nice supplement to the ideas in the haftarah itself, stressing real unity as a necessary and unavoidable phase of bringing the Jewish people back to the glory of a Temple, King, and close relationship with God.
In summary, then, the symbolic act of bringing two sticks together offered a model for national unity in which differences are retained, but all unite around a core set of issues and concerns.