Where in the Bible is being a member of the Body of Christ taught?
The truth that believers become members of the Body of Christ is taught in the writings of Paul, not in the Gospels or the Old Testament. Paul repeatedly teaches it, including Galatians 3:27, where the Holy Spirit baptizes believers into Christ. Romans is also identified as Paul's first book of doctrine.
Les explains that the unity believers share as members of the Body of Christ comes alone from the writings of Paul. He states plainly that this isn't taught in the Gospels or the Old Testament, but Paul is constantly at it: when we have faith in the Gospel, we become a member of the Body of Christ. Les then points to Galatians 3:27, explaining that if you have been baptized by the Holy Spirit's work into the Body of Christ, you have put on Christ. He also goes back to Romans, calling it the first Book of Doctrine that Paul writes in our New Testament, and says this is where we have to spend most of our time.