Herod Antipas beheaded John and did not give him a formal trial, thereby breaking the Mosaic code. We see in Matthew 14:9 that Herod did this because he wanted to save face and not look like a fool in front of his guests. Many of the sins we commit are done in order to save face. How many little white lies have you told because you are more concerned with looking good in front of others than you are with pleasing God?
For further study:
The Bible in a year: