Two Houses Now United: The House of Israel and House of Judah Restored as One

Were Abraham, Isaac, and Jacob Jewish? No! Before the break of the united monarchy ca 930 BC, there were NO JEWS. There were Hebrews who became the nation of Israel, which then split into the House of Judah and the House of Israel.  Despite this historical fact, nearly every modern Jew uses the term loosely to mean any descendant of Abraham, Isaac, and Jacob; there are many that anachronistically refer to the Jews in Egypt and the Jews at Mt Sinai. So what? Not understanding this seemingly minor detail causes a lot of confusion about who is a Jew, who are gentiles, and even what is the church. 
The central focus of the New Covenant was to reunite the two houses and make them one again!
Jer 31:31 “Behold, the days are coming, says the LORD, when I will make a new covenant with the house of Israel and with the house of Judah.
The united kingdom became two houses because God divided it due to their forsaking God by not doing what was right in his eyes. Ten of the tribes (the House of Israel) were given to Jeroboam, and two (Judah and Benjamin) remained for the House of Judah.
1Kgs 11:31-33 ‘Behold, I will tear the kingdom out of the hand of Solomon and will give ten tribes to you ‘(but he shall have one tribe for the sake of My servant David, and for the sake of Jerusalem, the city which I have chosen out of all the tribes of Israel), ‘because they have forsaken Me, and worshiped Ashtoreth…and have not walked in My ways to do what is right in My eyes and keep My statutes and My judgments, as did his father David.
After the death of Solomon, that his son, Rehoboam, tried unsuccessfully to restore the united monarchy:
1Kgs 12:21 And when Rehoboam came to Jerusalem, he assembled all the house of Judah with the tribe of Benjamin, one hundred and eighty thousand chosen men who were warriors, to fight against the house of Israel, that he might restore the kingdom to Rehoboam the son of Solomon.
The House of Israel went further and further away from God’s instructions becoming ever more adulterous, so God swore to not have mercy on the House of Israel though he would have mercy on the House of Judah:
Hos 1:6-7 “…For I will no longer have mercy on the house of Israel, But I will utterly take them away. Yet I will have mercy on the house of Judah…”
God stated that he was longer their God and they weren’t is people:
Hos 1:9 Then God said: “Call his name Lo-Ammi, For you are not My people, And I will not be your God.
He even stated that He divorced the House of Israel and exile her:
Jer 3:8 “… for all the causes for which backsliding Israel had committed adultery, I had put her away and given her a certificate of divorce…
Nevertheless, God promised to mercifully restore the House of Israel and to make her his bride:
Hos 2:19 “I will betroth you to Me forever; Yes, I will betroth you to Me In righteousness and justice, In lovingkindness and mercy.
Not only would he restore the House of Israel, but he would mend the division between the two Houses and make them one. He illustrated this with two sticks in Ezekiel’s hands, which represented the two houses restored:
Ezek 37:19 “say to them, ‘Thus says the Lord GOD: “Surely I will take the stick of Joseph, which is in the hand of Ephraim, and the tribes of Israel, his companions; and I will join them with it, with the stick of Judah, and make them one stick, and they will be one in My hand.”
A main point of Paul’s teaching is that the two houses have been restored and the middle wall of separation has come down:

Eph 2:11-16 Therefore remember that you, once Gentiles in the flesh…Eph 2:12 that at that time you were without Christ, being aliens from the commonwealth of Israel and strangers from the covenants of promise, having no hope and without God in the world. But now in Christ Jesus you who once were far off have been brought near by the blood of Christ. For He Himself is our peace, who has made both one, and has broken down the middle wall of separation, having abolished in His flesh the enmity, that is, the law of commandments contained in ordinances, so as to create in Himself one new man from the two, thus making peace, and that He might reconcile them both to God in one body through the cross, thereby putting to death the enmity.

This was prophesied in nearly every prophet and it is the heart and soul of the New Covenant: the House of Judah (Jews) and the House of Israel have been reconciled so that there is no longer a middle wall; they are no longer two sticks but one! This is the fulfillment of the New Covenant which the Father spoke of through Jeremiah:

Jer 31:31 “… I will make a new covenant with the house of Israel and with the house of Judah.
Paul consistently taught the good news of the New Covenant in his writings demonstrating what Jesus did through his death, freeing the divorced and adulterous wife, Israel, from her perpetual state of divorcee/whore status.
Rom 7:2-4 For the woman who has a husband is bound by the law to her husband as long as he lives. But if the husband dies, she is released from the law of her husband. So then if, while her husband lives, she marries another man, she will be called an adulteress; but if her husband dies, she is free from that law, so that she is no adulteress, though she has married another man. Therefore, my brethren, you also have become dead to the law [of the husband] through the body of Christ, that you may be married to another–to Him who was raised from the dead, that we should bear fruit to God.
Consequently, the two houses can reunite as one, without the wall, and will never be two nations:
Ezek 37:22 “and I will make them one nation in the land, on the mountains of Israel; and one king shall be king over them all; they shall no longer be two nations, nor shall they ever be divided into two kingdoms again.
While the absolute fulfillment of this will only be realized completely in the age to come, the inception happened at the cross and therefore there is technically no longer any distinction between the two houses…which is what Paul repeatedly said:
Rom 10:12 For there is no distinction between Jew and Greek, for the same Lord over all is rich to all who call upon Him.
And again:
1Cor 12:13 For by one Spirit we were all baptized into one body–whether Jews or Greeks, whether slaves or free–and have all been made to drink into one Spirit.
And again:
Gal 3:28 There is neither Jew nor Greek, there is neither slave nor free, there is neither male nor female; for you are all one in Christ Jesus.
Paul spoke of the House of Israel as “gentiles” because that is where they were scattered… first foretold in Leviticus:
Lev 26:33 I will scatter you among the nations [ba’goim בַגּוֹיִ֔ם, Greek ἔθνος ethnos=gentiles]
And later in Deuteronomy:
Deut 4:27 “And the LORD will scatter you among the peoples,  and you will be left few in number among the nations [ba’goim בַגּוֹיִ֔ם, Greek ἔθνος ethnos=gentiles] where the LORD will drive you.
Before God scattered them, He first split the united nation into two nations:
2Kgs 17:21 For He tore Israel from the house of David, and they made Jeroboam the son of Nebat king. Then Jeroboam drove Israel from following the LORD, and made them commit a great sin.
Then day came when God made good on this warning against Israel:
2Kgs 17:23 until the LORD removed Israel out of His sight, as He had said by all His servants the prophets. So Israel was carried away from their own land to Assyria, as it is to this day.
Through the prophet Hosea, God confirmed they would be scattered among the gentiles:
Hos 9:17 My God will cast them away, Because they did not obey Him; And they shall be wanderers among the nations [ba’goim בַגּוֹיִ֔ם, Greek ἔθνος ethnos=gentiles].
When we speak of the Kingdom of God, there is no longer a House of Judah (Jews) and House of Israel (who were scattered to the gentiles/nations). As far as tribes go, there were twelve tribes and there always will be twelve tribes, as evidenced by the twelve tribes in Revelation 7 and 14 and by the twelve gates of the New Jerusalem. Hence, there will always be those who are from the tribe of Judah and those from the tribe of Levi, Benjamin, Asher, Naphtali, etc. But these twelve tribes are no longer divided in two nations – they are now one.
In conclusion, Abraham, Isaac, and Jacob, were not Jews; they were Hebrews. Jacob’s sons became the Israelites and when the nation split, two nations emerged known as the House of Judah and the House of Israel. God divorced the House of Israel because of their incredible adultery and then scattered them to the nations/gentiles. He promised to remarry them back and the only way for that to happen was for Immanuel to die thereby cancelling the initial marriage contract (Old Covenant). When he arose, He was free to marry her under a new marriage contract (New Covenant)  in Jesus’ blood. This new covenant brings the two houses together and the two shall never again be two nations.
If you are under the New Covenant, you have come either from the House of Judah or the House of Israel (who were wanders among the gentiles). You might be genetically Hebrew but if you aren’t then you are part of the mixed multitude. Assuming you are not Jewish, then you are no longer a “gentile”: you have been grafted in to the commonwealth (all twelve tribes) of Israel! You are now a Hebrew and you can enter the kingdom through the work of Jesus on the cross, who removed the middle wall of separation between the House of Israel and the House of Judah.