I've been memorizing Romans 12 in the NIV and verses 4-6a relate especially well to life in a Relational Group such as ours: "Just as each of us has one body with many members, and these members do not all have the same function, so in Christ we who are many form one body, and each member belongs to all the others. We have different gifts according to the grace given us."
The thought that "each member belongs to all the others" could be scary to us individualistic North Americans, but remember that the analogy is that of the human body in which the members belong to each other in the sense that they are unified in a mutually supportive whole. It is the head that rules the body as we submit to him by his Spirit.
Paul then goes on in verses 6b-8 to list many of the spiritual gifts that the Spirit has placed in the body: prophecy, serving, teaching, encouraging, contributing to the needs of others, leadership, showing mercy, along with hints on how the different gifts should be exercised, perhaps fundamentally, as with prophecy, in proportion to our faith.
In the large Sunday assembly, only a relatively few members get to exercise their gifts because of the large number of members present, but in the relational groups everyone has this opportunity. And when this begins to happen, there is mutual blessing--and great joy.--David