In Mark 10, James and John presumed Jesus was going to set up a kingdom like Caesar's or Herod's, only properly this time, with the right people getting the top jobs. That was just a reshuffling of the cards. Jesus says, 'We need a whole new pack of cards.'
Wright essentially discusses how we as believers too often assume our job is to make the world the kingdom of God, using the methods the world uses if necessary. We've got it terribly wrong if we do that, whether we're talking about nuclear options (in discussion or "diplomacy") or church as business (the pastor-as-CEO stuff). Jesus, as usual, says we have to blaze a new trail, take the road never traveled, and announce the kingdom in deed and word.
Download the whole sermon. (NOTE: Not great sound quality, but worth it.)