Enmity divided all men, but it was especially characteristic on religious ground, inwardly and spiritually, between Jews and Gentiles. Therefore the Apostle could have had this enmity in mind as especially important.
At the same time, he undoubtedly had particular reasons for speaking at length about the reconciliation of Jews and Gentiles in Christianity. It is known how long this enmity persisted afterward, and how it continues to this day among unconverted Jews.
They would of course be changed at once if they became Christians, and with that became new men. Concerning this St. John Chrysostom said: "The Gentile did not become a Jew, but both came into a new condition.
He abolished the law not in order to transform one into the other, but to re-create both. 'That He might create both in Himself,' he says, first as though melting both down, that is, the Greek and the Jew.
He created one wondrous being, that is, the Christian, Himself becoming the first creation of this kind. This creation is far higher than the first creation.
'In Himself' may also mean that He first presented us with the pattern and example. He transformed both the Jew, who was circumcised and under the curse, and the Greek, who was outside the law, into one new man, higher than both Jew and Greek.
He made peace both in relation to God and in relation to one another. The Jew draws near to the Greek only when he becomes a believer."
We are not less saved, and they are not more saved. Both we and they have been counted worthy of one and the same grace, for Christ destroyed the enmity by His death and made us beloved to the Father through the Spirit.
His death killed, pierced through, and destroyed the enmity. He did not say "loosed," nor did he say "removed," but "killed," the strongest word. Thus that enmity will never rise again.
We can produce another enmity, but certainly not the first, which has been killed forever. But let us consider how terrible it is for us voluntarily to come again into enmity with God after He has done so much for our reconciliation.
This new enmity no longer awaits baptism, but Gehenna; not forgiveness, but punishment."
According to Blessed Jerome, "the creation of the new man will appear full and complete when heaven and earth are united, when there will be a new heaven and a new earth (Isa 65:17), when we shall drink the cup of Jesus new in the Kingdom of God (Mk 14:25), and sing a new song (Ps 97:1)."