Understanding what it means to be faithful in our task of evangelism is vital. Tim Keller does a great job in showing that the fundamental aspect of witnessing in a culture is confronting the idols of that culture. We can proclaim truth to a culture with very little response because we are not confronting the things they truly worship. We must get at the things people actually trust in if we are going to be faithful proclaimers of truth.
The Grand Demythologizer: The Gospel and Idolatry.