God will rejoice over redeemed Israel

Before He created the earth God chose who He would save[a]; sinners He would reconcile to Himself through the substitutionary life and death of Jesus the Christ [b].
This “election”, this choosing by God, did not depend on any good or bad God foresaw people would do, but only on His sovereign will. [c]
This choice of God, choosing to save some and not others, applies to all peoples, including Israelites. [d]
There will come a future time when every Israelite on earth will be saved, reconciled to God through Jesus Christ. [e]
When God restores and blesses Israel, with all her citizens reconciled to God through Jesus Christ, God will greatly rejoice. [f]

[a] Ephesians 1.4

[b] 2 Corinthians 5.17-21

[c] Romans 9

[d] Romans 11.7 (ESV), “What then? Israel failed to obtain what it was seeking. The elect obtained it, but the rest were hardened.”

[e] Romans 11:25–27 (ESV), “Lest you be wise in your own sight, I do not want you to be unaware of this mystery, brothers: a partial hardening has come upon Israel, until the fullness of the Gentiles has come in. 26And in this way all Israel will be saved, as it is written, “The Deliverer will come from Zion, he will banish ungodliness from Jacob”; 27“and this will be my covenant with them when I take away their sins.”

[f] Zephaniah 3:17–20 (ESV), “The LORD your God is in your midst, a mighty one who will save; he will rejoice over you with gladness; he will quiet you by his love; he will exult over you with loud singing. 18’I will gather those of you who mourn for the festival, so that you will no longer suffer reproach. 19Behold, at that time I will deal with all your oppressors. And I will save the lame and gather the outcast, and I will change their shame into praise and renown in all the earth. 20At that time I will bring you in, at the time when I gather you together; for I will make you renowned and praised among all the peoples of the earth, when I restore your fortunes before your eyes,’ says the LORD.”