How are we to be set apart?

I just finished a book called Colossians Remixed. I had wanted to read it for a while, and it was pretty good. The basic idea is to imagine what Colossians would read like in a current, post-modern, pluralistic setting. The authors purport that Paul was largely explaining to the church in Colossae how they should be different than the dominant culture of the day, the Roman Empire, and if he wrote it today, it would be encouraging churches to reject global capitalism. They even rewrote much of the book in this light. It was pretty good and thought provoking, but also pretty extreme at points. It did have interesting thoughts about what is meaningful to people in post-modern culture, and how Christians can have an impact on this culture.
It made me think, if the church is called to be set-apart, how it should be set apart from the culture we live in today. If we are to be the light of the world, how can we lead and demonstrate what God's kingdom should look like. According to Colossians remixed, we should be leading the way in environmentalism, fair trade initiatives, social justice issues, etc.