Being a Christian means being filled with God. It doesn’t mean you’re a better person. Rather, it means you’re a better person than you were before you became a Christian.
If you’re filled with God, then something of God will show in your life, because he’s there inside of you. If it doesn’t then you’re not a Christian but merely pretending to be.
God is a person of order and love, peace and of joy, so a person filled with God will inevitably start to show these characteristics of God in their own lives. That’s what ‘godliness’ means. A Christian will show in their life the peace of God which passes all understanding, because the God of peace lives in them.
This peace always manifests itself — initially at least — in small ways. Wherever we go, wherever we live, wherever we eat, sleep, work, or whatever, we take the God of peace in our hearts with us. He inspires us to acts of goodness. We offer praise and thanks; we encourage others; we actively console; we work to reconcile. In each of these small ways, we make the world a better place.
In time, and with enough people seeking to serve God in these ways, my peace joins up with your peace. The small instances of love occurring through my life join up with the instances of love expressed in yours. In all these ways, we stand up to the violence and hatred in the world. We stand up to the evil and intolerance. If enough of us live in this way, then the peace of God which passes all understanding becomes a reality. So let it start with us.