Because He Has Kept His Covenant with Israel
Now the Lord said to Abram, “Go from your country and your kindred and your father’s house to the land that I will show you. And I will make of you a great nation, and I will bless you and make your name great, so that you will be a blessing. I will bless those who bless you, and him who dishonors you I will curse, and in you all the families of the earth shall be blessed.”
Because He Established the Standard of Holiness through Israel
Now therefore, if you will indeed obey my voice and keep my covenant, you shall be my treasured possession among all peoples, for all the earth is mine; and you shall be to me a kingdom of priests and a holy nation.’ These are the words that you shall speak to the people of Israel.”
Because He’s Shown Grace and Justice through Israel
The Lord passed before him and proclaimed, “The Lord, the Lord, a God merciful and gracious, slow to anger, and abounding in steadfast love and faithfulness, keeping steadfast love for thousands, forgiving iniquity and transgression and sin, but who will by no means clear the guilty, visiting the iniquity of the fathers on the children and the children's children, to the third and the fourth generation.”
Because He Established His Home through Israel
2 Samuel 7:13-16
He shall build a house for my name, and I will establish the throne of his kingdom forever. I will be to him a father, and he shall be to me a son. When he commits iniquity, I will discipline him with the rod of men, with the stripes of the sons of men, but my steadfast love will not depart from him, as I took it from Saul, whom I put away from before you. And your house and your kingdom shall be made sure forever before me. Your throne shall be established forever.’”
Because He’s Shown Love through Israel
The Spirit of the Lord God is upon me, because the Lord has anointed me to bring good news to the poor; he has sent me to bind up the brokenhearted, to proclaim liberty to the captives, and the opening of the prison to those who are bound; to proclaim the year of the Lord's favor, and the day of vengeance of our God; to comfort all who mourn; to grant to those who mourn in Zion— to give them a beautiful headdress instead of ashes, the oil of gladness instead of mourning, the garment of praise instead of a faint spirit; that they may be called oaks of righteousness, the planting of the Lord, that he may be glorified. They shall build up the ancient ruins; they shall raise up the former devastations; they shall repair the ruined cities, the devastations of many generations.
Because the Savior was Born as a Jew
The book of the genealogy of Jesus Christ, the son of David, the son of Abraham.
Abraham was the father of Isaac, and Isaac the father of Jacob, and Jacob the father of Judah and his brothers, and Judah the father of Perez and Zerah by Tamar, and Perez the father of Hezron, and Hezron the father of Ram, and Ram the father of Amminadab, and Amminadab the father of Nahshon, and Nahshon the father of Salmon, and Salmon the father of Boaz by Rahab, and Boaz the father of Obed by Ruth, and Obed the father of Jesse, and Jesse the father of David the king.
And David was the father of Solomon by the wife of Uriah, and Solomon the father of Rehoboam, and Rehoboam the father of Abijah, and Abijah the father of Asaph, 8 and Asaph the father of Jehoshaphat, and Jehoshaphat the father of Joram, and Joram the father of Uzziah, and Uzziah the father of Jotham, and Jotham the father of Ahaz, and Ahaz the father of Hezekiah, and Hezekiah the father of Manasseh, and Manasseh the father of Amos, and Amos the father of Josiah, and Josiah the father of Jechoniah and his brothers, at the time of the deportation to Babylon.
And after the deportation to Babylon: Jechoniah was the father of Shealtiel, and Shealtiel the father of Zerubbabel, and Zerubbabel the father of Abiud, and Abiud the father of Eliakim, and Eliakim the father of Azor, and Azor the father of Zadok, and Zadok the father of Achim, and Achim the father of Eliud, and Eliud the father of Eleazar, and Eleazar the father of Matthan, and Matthan the father of Jacob, and Jacob the father of Joseph the husband of Mary, of whom Jesus was born, who is called Christ.
Because He Established His Kingdom through the Jewish People
Hebrew 7: 1-3 and 22-25
For this Melchizedek, king of Salem, priest of the Most High God, met Abraham returning from the slaughter of the kings and blessed him, and to him Abraham apportioned a tenth part of everything. He is first, by translation of his name, king of righteousness, and then he is also king of Salem, that is, king of peace. He is without father or mother or genealogy, having neither beginning of days nor end of life, but resembling the Son of God he continues a priest forever.
This makes Jesus the guarantor of a better covenant.
The former priests were many in number, because they were prevented by death from continuing in office, but he holds his priesthood permanently, because he continues forever. Consequently, he is able to save to the uttermost those who draw near to God through him, since he always lives to make intercession for them.
Because He Hasn't Rejected Israel
I ask, then, has God rejected his people? By no means! For I myself am an Israelite, a descendant of Abraham, a member of the tribe of Benjamin.
Because Israel Supports our Faith
do not be arrogant toward the branches. If you are, remember it is not you who support the root, but the root that supports you. Then you will say, “Branches were broken off so that I might be grafted in.” That is true. They were broken off because of their unbelief, but you stand fast through faith. So do not become proud, but fear. For if God did not spare the natural branches, neither will he spare you.
Because He will Dwell with all of His family, Together
And I heard a loud voice from the throne saying, “Behold, the dwelling place of God is with man. He will dwell with them, and they will be his people, and God himself will be with them as their God.