First off, both the Jewish Faith and Christian Faith recognize the Old Testament, but even the most Orthedox Jew no longer has the infrastructure in place to follow through on Biblical punishment, and Christians follow the teachings of Christ where the sin is still a sin, but we leave it in God's hands.
Second, this is about removing right and wrong from the world and making everything the same. Liberals can not stand the idea that there are moral absolutes that define right and wrong. In the 60's a book came out titled I'm OK, You're OK. This pushed the idea of no moral absolutes and no competitive reward. We are seeing this idea grow year after year.
If this Mayor wants to hear the sermons she can attend a service, or she can tie a criminal suspect to a crime and testimony that implicates the pastor and their sermon, then she can subpoena the text for criminal activity. Until then I refer her to the First Amendment.