When and for what reason was John beheaded?

Answer 1

John was imprisoned for criticizing the immoral marriage of Herod to Herodias, his sister-in-law. When Herodias and her daughter, Salome, plotted together, they convinced Herod to kill John, although he was reluctant. The famous story is that Salome danced for the king and his friends, and Herod said she could have whatever she wanted, so she asked for John's head on a platter. Herod gave it to her.

The Jewish historian Josephus tells us what probably did happen. He says that Herod Antipas had the Baptist arrested and killed in the castle of Macherus, east of the Dead Sea, because he disapproved of Antipas' marriage to his own brother's wife, who divorced her husband in order to marry Herod Antipas. The wedding took place in 34 CE and the execution of John would have been in 35 or 36 CE. The relevant text from Book 18 of Antiquities of the Jews:

"Now many people came in crowds to him, for they were greatly moved by his words. Herod, who feared that the great influence John had over the masses might put them into his power and enable him to raise a rebellion (for they seemed ready to do anything he should advise), thought it best to put him to death. In this way, he might prevent any mischief John might cause, and not bring himself into difficulties by sparing a man who might make him repent of it when it would be too late. Accordingly John was sent as a prisoner, out of Herod's suspicious temper, to Macherus, the castle I already mentioned, and was put to death."