You asked

what specific 'wall' was paul referring to between jews and gentiles in his day?

The passage, plainly, with room to sit with it.

Ephesians 2:14

“For he is our peace, who made both one, and broke down the middle wall of partition,”

Paul wrote this letter to Christians in Ephesus, a major city in Asia Minor, likely in the 60s CE while imprisoned. He is explaining how Jesus' life and death brought together people from different backgrounds, particularly Jews and non-Jews (Gentiles), into a single community.

What divisions in our world today might Jesus call us to dismantle?

Keep thinking

Behind the textwhat were the social and religious tensions between jews and gentiles in ephesus at that time?
Across the Biblehow does the old testament's vision for israel's relationship with other nations relate to paul's message here?
For todayhow do we identify contemporary 'walls of partition' that keep people apart?

Read alongside it

Galatians 3:28
Paul speaks of unity in Christ overcoming other social distinctions like status and gender.
Isaiah 56:7
An Old Testament prophecy about God's house being a 'house of prayer for all peoples'.
Colossians 3:11
Another of Paul's letters emphasizing that in Christ, traditional ethnic and social divisions no longer define identity.

Ask your own follow-up