If you were able to look through the last few weeks of Philippians, you would see this progression to where Paul lands today. He has spoken about Christ’s humility saving us, how we seek to restore relationship with one another, and now he says we can/should do that without grumbling or complaining. Paul tells us to live this way, because in so doing, we will shine as lights in the world. The NIV translates this poetically with, “Then you will shine among them like stars in the sky…”