In ch. 6 the members of our body are to be presented as weapons of righteousness (Rom. 6:13) for warfare and service. In this chapter, however, our bodies are to be presented as a living sacrifice for the church life. This sacrifice is living because it has life through resurrection; it is not like the sacrifices in the Old Testament, which were all slain. This sacrifice is also holy because, positionally, it has been separated unto God by the blood of Christ from the world and from all persons, matters, and things that are common; and because, dispositionally, the natural life and the old creation have been sanctified and transformed by the Holy Spirit with God's life and God's holy nature for God's satisfaction. Thus, this sacrifice is well pleasing to God.
In Greek, bodies here is plural and sacrifice is singular. This indicates that, although many bodies are presented, they become one sacrifice, implying that, although we are many, our service in the Body of Christ should not be many individual services, separated and unrelated. All our service should constitute one whole service, and this service must be unique because it is the service of the one Body of Christ.