Every single part, even very small ones, of complicated machines like a car engine are vital to keep it running. In the same way every member of the body of Christ, the Church, is vital. Failure to do our part may hinder the whole body from functioning properly. Our failure to pray may result in loss of power. Our failure to witness may be the reason that someone doesn't hear the gospel. Our failure to support the church financially may hinder the work of evangelism or missions. Our little part, if neglected, can result in big problems in the Kingdom of God. The work of every member of the body, however small, is needed.
What part do you need to be playing?