Why is the body of Christ considered strictly a Pauline teaching?

Les explains that the body of Christ began to be called out through Paul, the apostle of the Gentiles, as he preached the gospel of the grace of God in Acts. Les teaches that being a member of the body of Christ matters more than belonging to any denomination, because without that membership a person is eternally lost. Once saved, the Holy Spirit places believers into the body of Christ, giving eternal life, eternal salvation, and the hope of glory. Les also notes that the church will not go into the tribulation, chiefly because the whole concept of the body of Christ is a revelation only of the apostle Paul. It is never found in the Old Testament and never alluded to in Christ's earthly ministry. It is strictly a Pauline revelation, wrapped up in the predominantly Pauline word mystery.