Changing Society?

For those Christians who believe that the Christian's job is to change the tone of society by preaching the Gospel to people with the result being conversion, I'd like to respectfully ask that they think again. By being involved in transforming society, the focus shifts from the person of the unbeliever to the condition of society. While theoretically yes, people who become Christians can have a positive effect on society, there is no guarantee that this will happen.