Cells (or micro churches) are agile. They are contextualized. They are missional, and highly relational. However, left to themselves, they are vulnerable and volatile. They need a connection to a larger body.
"Celebration" is when clusters of cell groups gather in one place. Rub shoulders with one another. Spur one another on in the faith. Celebrate the goodness of God, and make him famous.
The glowing embers of each micro church join in celebration. The Holy Spirit fans the flame and soon there is roaring revival fire.