The relationship between the Jews and the Church is problematic to some Christians. Here’s the way I see it:
(1) The end of the [Jewish] age is often mentioned in the NT — Acts 2:17, Hebrews 1:1, 1 Corinthians 10:11 and James 5:9 refer to the “these last days”, “the ends of the age”, and “the judge standing at the door”. These and other End Time references appear to point to the siege of Jerusalem and the destruction of the temple in Jerusalem in AD70. This destruction of the Jews’ worship centre and body politic ended the Jewish age. The Second Coming of the Lord Jesus Christ (e.g. 1 Thessalonians 4:13-17) is a future event, and both in manner and purpose is distinctly different.
(2) The apostle Paul makes distinctions between “the Jew, the Gentile, and the church of God” (1 Corinthians 10:32). The kingdom of God was to be taken from the Jews and given to “a nation (NT Greek: ethnos: people group) that would bring forth fruit in due season” (Matthew 21:43). Paul refers to this people as “a foolish nation” (Romans 9:19; 1 Corinthians 1:20-25) It (i.e. the Church) is comprised of both Jew and Gentile and is “one new man” — a newly created humanity in Christ (Ephesians 2:15).
This new body, this “new creation”, is “the Israel of God” (Galatians 5:18), the ethnicity of which is not natural but spiritual. (This, however, does not diminish the natural and cultural ethnic values of the body’s various members.)
(3) Ethnic Israel remains “blessed for the fathers’ sake”; i.e. for the sake of the promises God made to the patriarchs Abraham, Isaac and Jacob (Romans 11:28). This explains why the Jews as a people, and Israel as a nation, have survived, and will survive all that Jew-haters have done and will do in trying to exterminate them.
Jesus Christ is “the Lion of the tribe of Judah” — its Defender and rightful heir to King David’s throne — will ascend to that throne and rule over not only his people but all nations. Those who have followed the Lord Jesus in their lifetimes will rule with him and exercise degrees of authority according to his judgement of their individual faithfulness.