En bref
Jerusalem’s citizens had to go to the wilderness to hear John the Baptist, because there was no obedience or openness to the gospel of repentance in Jerusalem, not even in the temple.
Jerusalem had to go to the wilderness to hear the Word of God because in Jerusalem, where God was not served in accordance with his will, it was not heard any longer. Once again it was heard in the wilderness, just like was so often the case with so many Old Testament prophets who ministered far away from the temple.1
5 Les habitants de Jérusalem, de toute la Judée et de tout le pays des environs du Jourdain, se rendaient auprès de lui;