Romans 11:25-27: “For I would not, brethren, that you should be ignorant of this mystery, less you should be wise in your own conceits; that blindness in part has happened to Israel, until the fullness of the Gentiles come in. And so all Israel shall be saved; as it is written, there shall come out of Zionthe Deliverer, and shall turn away ungodliness from Jacob (Isa. 59: 20-21. For this is my covenant to them, when I shall take away their sins.”
The apostle does something here which he has done before---drops a big bomb of truth. At Rome, where the church was predominantly Gentile, he has to deal with the matter of pride and superior feelings (spiritual elitism). So this time he unveils the truth that the Gentiles will only be in the tree for a specified time. Their day of opportunity will come to an end.
The times of the Gentiles have been fantastic. The nations have risen to dazzling heights in terms of academic, technological achievements. In the Gentile era, prosperity and freedom have come to mankind wherever the gospel has been received. The Gentile believers could easily become conceited and feel their exalted position is permanent. To take the wind out of their sails, and check any conceit they might feel having the inside track with God, he tells them their present supremacy is temporary.
The Gentiles had better be careful not to lord it over God’s nation during the time of her humiliation. When one of the Lord's children is in the woodshed, the rest had best not say, "na-na-na-na-na".