‘The body of Christ’ is another term for the church as a whole, as indicated by Paul in his letter to the Church of Corinth in Greece: ‘The body is a unit, though it is made up of many parts; and though all its parts are many, they form one body. So it is with Christ. For we were all baptized by one Spirit into one body—whether Jews or Greeks, slave or free—and we were all given the one Spirit to drink' (1 Corinthians 12:12-13). ‘If one part suffers, every part suffers with it; if one part is honored, every part rejoices with it. Now you are the body of Christ, and each one of you is a part of it' (1 Corinthians 12:26-27).
It is also a reference to Luke 22:19, in which Jesus broke bread at the Last Supper and said, 'This is my body given to you; do this in rememberence of me'.