Christ teaches that there are two generations of Israel related to Jerusalem, its temple, and the future. The generation of his day, like the one in Jeremiah’s day, is unregenerate and unrepentant; they kill the prophets sent to them and remain unfaithful. This generation will see another destruction of their temple in their lifetime, as foretold by Daniel. Another generation, their offspring, will repent and respond to the gospel; they will experience the “new covenant” and be filled with the Holy Spirit. They will take part in the restoration of Israel, Jerusalem, and its temple in the messianic kingdom.
Based on his understanding of Isaiah, Paul also describes two generations of his fellow Jews: the Jews of his day, who were largely unrepentant and hostile to Christ and the gospel; and a future generation of repentant Jews, who will believe in their Messiah. Paul, too, connects this future generation of repentant Jews to the time when Israel experiences the messianic kingdom.
All of these events foretold by the prophets are as certain to occur on this Genesis earth as the fixed operation of the sun and the moon. And they will occur before heaven and earth truly pass away, when they are destroyed on the last day as Christ comes again to take his people to the new heavens and new earth.