For Herod had sent and seized John, and bound him in prison for the sake of Herodias, his brother Philip's wife; because he had married her. 18 For John said to Herod, "It is not lawful for you to have your brother's wife." 19 And Herodias had a grudge against him, and wanted to kill him. But she could not, 20 for Herod feared John, knowing that he was a righteous and holy man, and kept him safe. When he heard him, he was much perplexed; and yet he heard him gladly. Mark 6:17–20 (RSV)
Herod wanted to keep John the Baptist safe from Herodias. Herod knew in his heart that John spoke the truth about his marriage to Herodias. Herod and Herodias sinned by marrying, as Herodias' husband was still living. His lust for her and her lust for power drove them.
Still, a tiny flame of the fear of God flickered within Herod. He was glad to listen to John, though Herod was perplexed by what he heard. There was hope for Herod as John spoke God's Word. Even if we are confused by the Word, it can still work within us.
Then came the party, the dance, and Herod's promise. Herod had John murdered for the sake of his promise as he didn't want to look bad in front of his guests.
We must take care with the opinion of others. Listen, seek to understand, and grow from their insights is a helpful thing. However, if the opinion of others drives all our thoughts and choices, we will soon stop thinking for ourselves, doing what pleases them.
Jesus teaches that we can serve God with our whole being or serve some other god. We cannot do both. If what others think of us moves our hearts, we worship at the altar of public opinion. None of these will stand for us on the last day. Only Christ will stand on that Day.