What happens to the Jewish remnant when Christ returns?
When Christ returns and sets up His Kingdom, the Jewish remnant kept through the tribulation will see Him coming in the clouds of glory. They will believe in a moment; the nation will be born spiritually in a day, and the New Covenant becomes reality as God writes His law in their hearts.
Les explains that this will not be Israel's own choice, as though that company of Jews suddenly decided to follow God. Instead, when Christ returns and sets up His Kingdom, the remnant of Jews He kept through the tribulation period will see Him coming in the clouds of glory. They are going to believe in a moment. Les connects this to Isaiah 66, saying the nation will be born in a moment, and to the remnant Paul deals with in Romans 9, 10, and 11, so that all that nation of Israel is born in a day spiritually. Then the New Covenant becomes a reality, and God puts His Word and commandments in their heart, being their God and they His people.