Can you imagine someone rebuking a very prominent person in society over a sin? It is highly probable that your first reaction would be, "Oh my, that's foolish", or perhaps, "Is he out of his mind chasing down a well known public figure?" Perhaps the more objective part of you would say, "He may be right, but does he really need to be so firm about it?"
The person I'm referring to here is none other than John the Baptist. Now, John has a very peculiar personality, he doesn't live the way normal people live and he doesn't even wear ordinary clothes, but rather unconventional ones, suitable for his life in the wilderness. He already has features that can be picked and easily pointed at. But John seems focused on his prophetic ministry, on something more important, more serious. Rather than succumbing to the norm and going along in society without being noticed, he does something unusual, he calls out Herod's sin.
Is he trying to get attention by stating the sin of the king of Judea?
In that period of time, and perhaps also today, people would question the motives of John the Baptist. However, all these questions about motives do not reflect upon the core of the matter, which is the truth that Herod had taken his brother's wife as his own. He was living in sin, and John the Baptist was admonishing the King. "For John has been saying to Herod, 'It is not lawful for you to have your brother's wife." Mark 6:18. Herod, as King of Judea, was to be an example to his people and respect the religious commandments and live a life of righteousness before God.
With John the Baptist there were no exceptions or special favours given to the upper echelons of society. Interestingly, we don't read anything about the Pharisees or Sadducees saying anything about the moral life of King Herod.
What shall we do then? Are we all called to be like John the Baptist in confronting our brother or sister who is living in sin? But who am I to point out someone's sin? Shouldn't I first be looking at the plank in my own eyes and hence my own sins (Matthew 7:3)?
On one occasion, Jesus says, "If your brother sins, go and show him his fault when the two of you are alone. If he listens to you, you have regained your brother." Matthew 18:15
On another occasion, Jesus says to the woman, "Then neither do I condemn you. Go now and leave your life of sin." John 8:11
Even Peter received the rebuke from Paul when he confronted Peter about his hypocrisy; eventually, Peter had to reconcile his daily actions with what he was daily preaching.
We have a loving God, who reproaches us and rebukes us in His awesome tough love, giving us the chance to repent and reconnect with Him.