I have little doubt that during the life of Christ it would have been understood and spoken of that all who loved Christ were members of the body of Christ.
All scriptural references to the followers being one in Christ, parts of the body of Christ, unified in Christ, a family because of their love of Christ occurred after the death of Christ. So this would have been about 50CE.
Sadly the body, the family, those who were one in Christ have come apart like safety glass, today we have at least 45,000 shards of differing belief all claiming the exclusive truth of Christ's word.
