In Ephesians 3, Paul tells us the mystery of Christ which was hidden from previous generations was the union of the Jews and Gentiles in one body.
While many are advocating another gospel centered on the modern state of Israel, and building again the separating wall which Christ destroyed, the truth of the gospel declares that God’s eternal purpose in Christ Jesus is revealed through the one new man in Christ. It is through the church – Jews and Gentiles in Christ – that the manifold wisdom of God is revealed (Read Ephesians 2:11 -3:21).
God is not going to go contrary to the gospel of His Son by reverting back to national secular Israel, and blessing a man made temple with animal sacrifices and all that was associated with old testament Israel after the flesh. That covenant has been made obsolete and God has established a new covenant through the blood of Jesus Christ.
Paul describes these two covenants (the old and the new) in his epistle to the Galatians. Consider Galatians 4:22-31:
22 For it is written, that ABRAHAM HAD TWO SONS, the one by a bondmaid, the other by a freewoman.
23 But he who was of the bondwoman was born AFTER THE FLESH; but he of the freewoman was BY PROMISE.
24 Which things are AN ALLEGORY: for THESE ARE THE TWO COVENANTS; the one from the MOUNT SINAI, which gendereth to BONDAGE, which is Agar.
25 For this Agar is mount Sinai in Arabia, and answereth to JERUSALEM WHICH NOW IS, and is IN BONDAGE WITH HER CHILDREN.
26 But JERUSALEM WHICH IS ABOVE is free, which is the mother of us all.
27 For it is written, Rejoice, thou barren that bearest not; break forth and cry, thou that travailest not: for the desolate hath many more children than she which hath an husband.
28 NOW WE, BRETHREN, AS ISAAC WAS, ARE THE CHILDREN OF THE PROMISE.
29 But as then he that was born AFTER THE FLESH persecuted him that was born AFTER THE SPIRIT, even so it is now.
30 Nevertheless what saith the scripture? Cast out the bondwoman and her son: for THE SON OF THE BONDWOMAN SHALL NOT BE HEIR WITH THE SON OF THE FREEWOMAN.
31 So then, brethren, we are not children of the bondwoman, but of the free.
God, through Christ, as reckoned all in sin and will hold everyone accountable to the gospel of Jesus Christ. God has no special alternative for the Jew apart from the gospel of Jesus Christ revealed in the new testament. That is why the same gospel was first sent to the Jew and then to the Gentile. One gospel for all, so that all who believe can be united as one new man in Christ Jesus!