Individuals related to one another and working together can be a very strong force. This is true in the natural as well as the spiritual. The Tower of Babel is the story of man's cooperation as a community to achieve an end which was of the spirit, or disposition of the enemy: Pride.
In my natural circumstances, I work with a community of professionals. Our collegiality and effectiveness has drawn the attention of a Harvard educational researcher recently and won recognition from the Positive Behavior Support program of the North Carolina Department of Public Instruction. What we have together has been established over the years as a disposition to professionalism. It is a "spirit" we hold as a group. I note this here only as a real example of group dynamics which are not labeled a "spiritual" endeavor by most people. I see it routinely as a spiritual experience but that is another story.
The Body of Christ is identified by participants as a spiritual reality on earth. This entity, called the Church, is a composite of individuals. Each member is joined to the whole by an individual response to the gospel message of peace and reconciliation with God the Father through the finished work of Jesus on the cross. Once found in Christ and thus as a group member, individual believers have many responsibilities. These become or are sometimes mandated in the Bible as a mutually held responsibility of the Body, as well. Numerous places in the NT instruct believers to fulfill varied imperatives. Romans 12 is just one example. Effectiveness at these responsibilities is a consequence of only one issue, maturity in the spirit or disposition of Jesus. This maturity may be identified by individual and corporate fruit which is described by the Bible as fruit of the spirit. This fruiting is a function of abiding on the vine of Jesus. This "fruit" or evidence of maturity in Christ is that which reflects the spirit or disposition of Jesus.
Being at rest in the in-dwelling Christ and thus being fully clothed emotionally (being reactive and responsive to others based on a heart reality not an intellectual view) in the disposition of Jesus is maturity as a believer and produces the glorious earthly reality of Christian fellowship in spirit, which is church body life.