Worthy of the Gospel: The Roots of Fearless Unity in the Gospel

In the end of the first chapter and the second chapter of Paul's letter to the Philippians, Paul calls on believers to live a life worthy of the gospel, which is a life in harmony with the kingdom of God so as to call attention to the tremendous worth of the gospel.  This kind of life demonstrates unified love in the cause of the gospel and fearlessness before adversaries.  What are the roots of this fearless unity in love? How can we live a life that showcases the worthiness of the gospel?  And what can we learn from the examples of Jesus, Paul, Timothy, and Epaphroditus that will help us live in such a way?