Isaiah 27:6 says, "In days to come Jacob shall take root, Israel shall blossom and put forth shoots and fill the whole world with fruit." This beautiful picture of Israel's fruitfulness did not come to pass the way the physical descendants of Jacob might have expected. In fact, when Jesus came to Jerusalem at the beginning of the last week before His crucifixion, he made a pit-stop at a fig tree in order to teach His disciples a lesson.
In the morning, as he was returning to the city, he became hungry. And seeing a fig tree by the wayside, he went to it and found nothing on it but only leaves. And he said to it, "May no fruit ever come from you again!" And the fig tree withered at once. (Matthew 21:18-19)
What follows this cursing of the fig tree is a series of encounters with the chief priests and elders of Israel that culminates in Jesus telling the religious leaders, "Therefore I tell you, the kingdom of God will be taken away from you and given to a people producing its fruits" (Matthew 21:43).
Therefore, the amazing truth of Isaiah 27:6 is that it was written concerning us! It is the New Covenant Church - filled with Gentiles like me - that has blossomed, put forth shoots, and filled the earth with fruit! We wild branches have been grafted into the original people of God, we are to fulfill its purpose of being a light to the nations, and we are inheritors of all of the original promises to the patriarchs.
This ought to let us know, though, what God wants from His people: fruit. He doesn't save us from His wrath just so we can sit around doing nothing. He saves us and then produces fruit in us, and if there is no fruit, then there is no indication that He has saved us. Remember that the servant who buried his Master's money so that it produced no return was thrown into the outer darkness (Matthew 25:30).
So let those of us who know the Lord rejoice in His grafting of us into His family. Let us rejoice that He intends to produce His fruit in us throughout the world. But let us take heed lest we fail to do what He has created us to do.