I have had a long history of discussing this topic with friends and, while I consider the issue necessary to be nuanced (e.g., do Jews have to believe in Jesus as Messiah? And why is that not at some level superssionistic?), here is a good set of arguments to consider when one discusses this topic:
Supersessionism is the view that the New Testament Church supersedes, replaces, or fulfills the nation Israel’s place and role in the plan of God. I am convinced that supersessionism / replacement theology is an unbiblical doctrine that violates clear statements in both the Old and New testaments that teach and affirm a national salvation and restoration of Israel. Below are twelve reasons why supersessionism violates the biblical witness:
1. The Old Testament explicitly teaches the restoration of the nation Israel.
2. The Old Testament explicitly promises the perpetuity of the nation Israel (see Jer. 31:35-37).
3. The New Testament reaffirms the Old Testament expectation of a salvation and restoration of Israel.
4. The New Testament explicitly states that the Old Testament promises and covenants to Israel are still the possession of Israel even during this church age and even while the nation is currently in a state of unbelief (see Romans 9:3b-4).
5. The New Testament indicates that God is faithful to Israel because of His promises to the patriarchs of Israel (Romans 11:28).6. The New Testament indicates that Israel’s election/calling is irrevocable (Romans 11:29; see also Deuteronomy 7:6-8).
7. The New Testament never uses the term “Israel” for those who are not ethnic Jews. Thus, the church is never called “Israel.”
8. Supersessionists have failed to show that the New Testament identifies the church as “Israel.”
9. Supersessionists have failed to show that the New Testament reinterprets or alters the original OT prophecies in regard to Israel. The alleged “NT Priority” approach of Supersessionism is really ‘structural supersessionism’—a hermeneutic that does not allow the OT passages to speak to the issues they address.
10. Supersessionists have failed to show that unity between Jews and Gentiles in the church rules out a future restoration of the nation Israel.
11. Israelite language applied to believing Gentiles does not mean the church is Israel.
12. New Testament prophecy refers to Israel, thus indicating that God’s plan for Israel is alive.