"King Herod heard about this, for Jesus' name had become well known. Some were saying, 'John the Baptist has been raised from the dead, and that is why miraculous powers are at work in him.' Others said, 'He is Elijah.' And still others claimed, ' He is a prophet, like one of the prophets of long ago.'" NIV translation
The name of Jesus became well known and even the king heard about what was going on. All kinds of people were trying to figure out who He was and the same thing happens today. There are those who say that Jesus was a "good man" and some that say He was a prophet or even Elijah.
"But when Herod heard this, he said, 'John, the man I beheaded, has been raised from the dead!' For Herod himself had given orders to have John arrested, and he had him bound and put in prison. He did this because of Herodias, his brother Philip's wife, whom he had married. For John had been saying to Herod, 'It is not lawful for you to have your brother's wife.'" NIV translation
Herod was convinced that John the Baptist had returned from the dead. He had been arrested by Herod for calling him to repent for taking his brother's wife for himself. As the herald for Jesus, John went first calling people to repent and he did so for all men. It didn't make any difference whether it was a common man or even the king as John simply focused on his purpose.
There are a great many people, today, who will loudly proclaim the gospel as long as it is in a church. Many times, they will not stand up and preach the truth in the streets or in the halls of power. If we want to be true heralds for the return of Jesus Christ, we must faithfully proclaim the gospel even to people that don't want to hear it.
"So Herodias nursed a grudge against John and wanted to kill him. But she was not able to, because Herod feared John and protected him, knowing him to be a righteous and holy man. When Herod heard John, he was greatly puzzled; yet he liked to listen to him." NIV translation
Herodias wanted to kill John because she wanted to change husbands for wealth and power. Herod protected him because he new that he was holy and wanted to hear more of the gospel. God was simply giving John time to reach the king.