Why did Herod imprison John the Baptist?

Herod imprisoned John the Baptist due to John's fearless proclamation of the truth regarding Herod's adultery and sinful actions. In Mark 6:17-20, we learn that Herodias bore a grudge against John because he openly declared that Herod's marriage to her was not lawful. Herod respected John's character and sought to protect him from making a rash decision influenced by Herodias, yet the pressure from her ultimately led to John's beheading. This highlights the costly nature of speaking the truth in a world that often opposes God's commands.