what is rev. buckministers sermon about

From the text:

By now his father had gotten onto the woes of Jericho, and he was finding his stride. Jericho, his father announced, was a place that needed to be rooted out so that God's good and perfect purposes might be fulfilled. So God had brought to its walls the Hebrew host to be His hands to carry out His righteous work. Reverend Buckminster paused and cleared his throat. He paused some more and cleared his throat again. He looked down at Mrs. Buckminster. He looked away.