Judging me on my understanding of Christianity, are you?
While Jesus did intend to change the hearts of His Disciples, He also required them to do good works. Allowing our culture to slip into a sewer without any attempt to engage it is akin to allowing the hungry to starve or the naked to freeze.
The fallen world has rejected heaven. Heaven has not rejected the fallen world. It thrust itself into the world mightily with the Incarnation. G-d has not given up on it yet. We are called to advance heaven while we draw breath. We do so heart by heart, and also by establishing righteousness where we can.
Shalom.
The problem we face today is really quite simple: We are long past the point where we should be shaking the dust from our sandals and moving on; we just don't like to admit it because we don't know where to go.