To say that the Church replaced Israel is wrong, and the Church does not say that. We are adopted heirs owing our sonship and salvation to Jesus, the Messiah, for which the Jews had long awaited and whom God promised way back at the beginning.
Those Jews who reject Jesus are have chosen to remain under the old covenant. Those Jews who accept Jesus as the Messiah are under the new covenant.
There is no different covenant or dispensation from God to the Gentiles, it is one and the same.
God is unchanging and He told us through His prophets of the OT and we hear it from Jesus Himself, that the salvation Jesus brings is the salvation of ALL and that there is no distinction between Jew, Greek, Gentile, woman, man, slave or free.
God never withdrew His promises to Israel, they are fulfilled in Jesus and we are coheirs.
The Church says that this is the NEW Covenant of the NEW Israel, not a replacement of the old, but the PERFECTION of it.
Take that up with the CC and what it actually teaches.
877 Likewise, it belongs to the sacramental nature of ecclesial ministry that it have a collegial character. In fact, from the beginning of his ministry, the Lord Jesus instituted the Twelve as "the seeds of the new Israel and the beginning of the sacred hierarchy." Chosen together, they were also sent out together, and their fraternal unity would be at the service of the fraternal communion of all the faithful: they would reflect and witness to the communion of the divine persons. For this reason every bishop exercises his ministry from within the episcopal college, in communion with the bishop of Rome, the successor of St. Peter and head of the college. So also priests exercise their ministry from within the presbyterium of the diocese, under the direction of their bishop. [http://www.scborromeo.org/ccc/para/877.htm]
Just as the Old Testament is full of foreshadows of the New Testament (typology), Catholics believe the Bible is clear that the New Jerusalem of the Book of Revelation is not the historic city of Jerusalem. We do not believe that present day Israel is the same spiritual entity as the historic Israel before the time of Christ. After the crucifixion, the curtain of the Jewish sanctuary was torn in two (Mk 15:37-39, Lk 23:44-46, Mt 27:51) which was God tearing his cloths. At that point, a transfer of authority happened and we believe that the fledgling Church became the New Israel. [http://www.davidmacd.com/catholic/why_did_the_catholic_church_move_to_rome_from_jerusalem.htm]
“became the new Israel” is NOT saying they “joined” Israel.