Answer:The Church started at Pentecost in Acts chapter two and is a new body composed of both Jew and Gentile (Eph. 2:13-16). There are three groups of people in the world today. There are the unsaved gentiles, unsaved Jews, then there is the Church which is made up of both Jew and Gentile believers, trusting in Christ. That is, everyone in the Church is called a Christian and has been saved by grace, received a transformed heart, and has been indwelt, sealed and baptized by the Holy Spirit (Jer. 31:31; Ezek. 36:26; Eph. 2:8-9). The grounds of salvation is based upon who Jesus is and the testimony involves the gospel of Christ that we preach today, namely, the death, burial and resurrection of Jesus Christ (1 Cor. 15:1-5).
All Christians agree that to be saved today in the Church age one has to believe that Jesus is the Christ (1 John 5:1) and its basis is in Jesus Christ and Him alone. Scripture, however, makes it clear that all Israel, the ethnic seed of Abraham, Isaac, and Jacob will be saved and call on the name of the Lord. This is a clear teaching in the Old Testament from verses like Isaiah 62:1-4:
For Zion's sake I will not hold My peace, And for Jerusalem's sake I will not rest, Until her righteousness goes forth as brightness, And her salvation as a lamp that burns. The Gentiles shall see your righteousness, And all kings your glory. You shall be called by a new name, Which the mouth of the LORD will name. You shall also be a crown of glory In the hand of the LORD, And a royal diadem In the hand of your God. You shall no longer be termed Forsaken, Nor shall your land any more be termed Desolate; But you shall be called Hephzibah [“My delight is in her”], and your land Beulah [“a possession”]; For the LORD delights in you, And your land shall be married. (Isa 62:1-4)
God’s promise to ethnic Israel is also reaffirmed in the New Testament by passages like Romans 11:25-27:
For I do not desire, brethren, that you should be ignorant of this mystery, lest you should be wise in your own opinion, that blindness in part has happened to Israel until the fullness of the Gentiles has come in. And so all Israel will be saved, as it is written: "The Deliverer will come out of Zion, And He will turn away ungodliness from Jacob; For this is My covenant with them, When I take away their sins." (Rom 11:25-27)
Your question, though, seems to be “how” will God bring “all Israel” to Christ in the end, not necessarily, will God save “all Israel.” This is how Scripture describes the future of the three groups:
The Church will continue to spread the gospel of Christ, but just as apostasy hit Israel, so apostasy will grow great in the Church to the point where Christ’s Church will no longer be effective. Its message corrupt, its works perverted, and its appearance will be like the world, she no longer will it be set apart for holy service. The faithful of the Church will be raptured out of this world to be with the Lord in the air (1 Thes. 4:15-17).
The Gentiles will continue in sin, but with the righteous testimony of the Word removed and God’s word preached less and less, the nations will become more and more base, more cruel, more corrupt, more openly sinful. The picture of the unsaved given in Romans chapter 1, absent of God’s word, will reach its maturity and logical conclusion. A world that is described as having the characteristics of Babylon and Sodom and Gomorrah will result. As sin increases, so will slavery to sin and the governments of the world will remove freedoms in order to keep control. The government of the future is one of complete control in an effort to keep control and a semblance of peace. Anti-Semitism will grow and the governments of the world will not be kind to Israel.
The Nation Israel
National Israel will continue to come under increasing pressure and persecution. After the rapture of the Church, national Israel will come under extreme pressure and hatred. Israel as a nation will continue to have a hardened heart (Rom. 11:12) though many certainly will come to the Lord. But, as the world comes against them as a people group they will experience extreme persecution, to the point where, by the time the Lord returns at the end of the Tribulation, there will be fewer than one third of mankind left alive. The Tribulation is the seven year period the Jews call the time of Jacobs trouble (Jer. 30:5-7) and the day of the Lord (Isa. 13:9-16; 34:1-8; Joel 1:15-2:11, 28-32; 3:9-12; Amos 5:18-20; Obad. 15-17; Zeph. 1:7-18). The Tribulation starts at the signing of the peace agreement for Israel (Dan. 9:24-17). It is at the end of this terrible period in human history that Scripture says “all” the Jews that survive will “call upon the Lord.” The Tribulation period is described as “birth-pangs” as it is the preparation period for bringing in the Davidic Kingdom (Isa. 66:7-13; Matt. 24:8; 1 Thes. 5:2-5). Notice the picture drawn by Isaiah:
Why is Your apparel red, And Your garments like one who treads in the winepress? "I have trodden the winepress alone, And from the peoples no one was with Me. For I have trodden them in My anger, And trampled them in My fury; Their blood is sprinkled upon My garments, And I have stained all My robes. For the day of vengeance is in My heart, And the year of My redeemed has come. I looked, but there was no one to help, And I wondered that there was no one to uphold; Therefore My own arm brought salvation for Me; And My own fury, it sustained Me. I have trodden down the peoples in My anger, Made them drunk in My fury, And brought down their strength to the earth." I will mention the lovingkindnesses of the LORD And the praises of the LORD, According to all that the LORD has bestowed on us, And the great goodness toward the house of Israel, Which He has bestowed on them according to His mercies, According to the multitude of His lovingkindnesses. For He said, "Surely they are My people, Children who will not lie." So He became their Savior. (Isa 63:2-8)
Everyone that survives the Tribulation will believe that Jesus is the Christ, the promised Messiah of the Old Testament. That includes all ethnic Israel, all who are left will be transformed and receive the New Covenant promise of Ezekiel 36:22-30:
Therefore say to the house of Israel,`Thus says the Lord GOD: "I do not do this for your sake, O house of Israel, but for My holy name's sake, which you have profaned among the nations wherever you went. "And I will sanctify My great name, which has been profaned among the nations, which you have profaned in their midst; and the nations shall know that I am the LORD," says the Lord GOD, "when I am hallowed in you before their eyes. For I will take you from among the nations, gather you out of all countries, and bring you into your own land. Then I will sprinkle clean water on you, and you shall be clean; I will cleanse you from all your filthiness and from all your idols. I will give you a new heart and put a new spirit within you; I will take the heart of stone out of your flesh and give you a heart of flesh. I will put My Spirit within you and cause you to walk in My statutes, and you will keep My judgments and do them. Then you shall dwell in the land that I gave to your fathers; you shall be My people, and I will be your God. I will deliver you from all your uncleanliness. I will call for the grain and multiply it, and bring no famine upon you. And I will multiply the fruit of your trees and the increase of your fields, so that you need never again bear the reproach of famine among the nations. (Eze 36:22-30)
Thanks for asking.
Dr. John Pappas