What Exactly was The Baptist Saying?

John the Baptist is a central figure in Christianity. Sent by God as shown by the prophets, he prepared the way of the Lord, the way of Jesus Christ (Malachi 3:1, Mt 3:3, 11:10). John was of the priestly Levitical tribe in the order of Abijah, being born of Zechariah and Elizabeth, both of whom were of Levi (1 Ch 24:10, Luke 1:5). When John was preaching and baptizing, it is important to note for this question, he did so apart and away from the temple in Jerusalem. He preached in the wilderness. He baptized in the Jordan. (See Mt. 3:1, Mar 1:4.) The point is he did this without reference to the Levitical system of confession of sin and sacrifice. (See Lev 4, 23, etc.) With these things in mind, from a Trinitarian position, what exactly was John the Baptist preaching apart from the temple system when he said repent? Repent means change your mind. Metanoeo, Strong's G3340, to think differently, to reconsider. How would this change prepare the way of the Lord? How would it make straight His paths?