John's most powerful foe was Herod Antipas, the tetrarch of Galilee. Herod and John had an interesting relationship because Herod respected John, yet at the same time he feared what he perceived to be John's growing political power because of the prophet's popularity.
Josephus provides a bit of background the Bible lacks. Herod was married to the daughter of Aretas, king of Petra. However, before John became a popular figure, Herod divorced her and married his sister-in-law, Herodias. This caused a problem, as Herodias was already married to Herod's brother, Philip. At this point, a convergence takes place between John's rising influence with the people and Herod and Herodias' adulterous and incestuous marriage, which clearly violates the sexual purity laws in Leviticus 18.
Josephus writes that Herod took John prisoner because he feared the prophet's prominence, believing that rebellion against his rule was growing in response to John's preaching. Apparently, during John's captivity, he warned Herod that he and Herodias were in an adulterous relationship.
Thus, when a convenient occasion presented itself, Herodias took her revenge, getting away with John's murder because of Herod's foolish timidity. Subsequently, Aretas came against Herod in war, seeking revenge for Herod divorcing his daughter. Josephus writes that Aretas soundly defeated Herod's forces. The people of Judea concluded that Herod's defeat was God's punishment for taking John's life.
John W. Ritenbaugh
Elijah and John the Baptist