Romans 11:25-27
“For I do not want you, brethren, to be uninformed of this mystery -so that you will not be wise in your own estimation -that a partial hardening has happened to Israel until the fullness of the Gentiles has come in; and so all Israel will be saved; just as it is written, “THE DELIVERER WILL COME FROM ZION, HE WILL REMOVE UNGODLINESS FROM JACOB. THIS IS MY COVENANT WITH THEM, WHEN I TAKE AWAY THEIR SINS.“
God’s annual holy days reveal that this is not the only “day of salvation”—that He is working with only a relative few right now, and the rest of mankind will have an opportunity for salvation either during the Millennium or after the Second Resurrection. Passover, the Feast of Unleavened Bread, and Pentecost hold great significance for the firstfruits who have already made the New Covenant, but they have little spiritual meaning for the Israelites who have not. Next, the Feast of Trumpets, the pivot point in the holy day calendar, is meaningful for firstfruits, for Israelites, and for all of mankind because it pictures the return of Christ to establish His Kingdom on earth.
After that are the holy days associated with the second harvest, the fall harvest—particularly the Feast of Tabernacles, which pictures the Millennium when the resurrected and glorified firstfruits will have responsibilities. Yet, the greater meaning concerns Israel. The remnant of Israel—those who survive Jacob’s Trouble—will then have the opportunity to make the New Covenant, even though, as a nation, they will not be a part of the first resurrection.
The apostle Paul goes to great lengths to explain this phased approach to salvation, using the metaphor of an olive tree with natural branches, representing Israel, being broken off, and wild branches—Gentiles—being grafted in (Romans 9-11). To summarize, Paul explains that God will use the Gentiles, and by implication, those making the New Covenant now to make the majority of Israel jealous, to bring them back to Him when they see the spiritual blessings. That covenant, then, will be available throughout the Millennium and into the time of the Second Resurrection.