Justice, Power, and the Kingdom

We have been spending some time in LIFE groups reading and watching bits from Brian McLaren in preparation for his visit here in Portland. Recently groups had some excellent reflection on this clip. McLaren says "Worldly systems are unified by their love of power. The Kingdom of God is about the Power of Love." How can we, as Christians, show our unity in the power of love? When is this easy? When is it more difficult?