“He is the voice
Of one crying out
In the wilderness.
‘Prepare the way
Of the Lord!
Make his paths
Straight!’”
φωνὴ βοῶντος ἐν τῇ ἐρήμῳ Ἑτοιμάσατε τὴν ὁδὸν Κυρίου, εὐθείας ποιεῖτε τὰς τρίβους αὐτοῦ,
Just as in Matthew, chapter 3:3, Mark has this citation from Isaiah about John the Baptist. Both Mark and Matthew have this exact same quotation, word for word from Isaiah, chapter 40:3. John, chapter 1:23, and Luke, chapter 3:4, have this very same quotation. John used it as an explanation of who John the Baptist was. Originally in Deutero-Isaiah, this was about preparing a new path or a way out of the Exile, just as there was the path of the Exodus. In this wilderness or desert, they were to make a straight path, like a highway for God or the holy way to prepare a path for Yahweh. However, it is clear that John the Baptist was the messenger being sent ahead. He was a voice crying out in the wilderness (Φωνὴ βοῶντος ἐν τῇ ἐρήμῳ) to prepare the way of the Lord (Ἑτοιμάσατε τὴν ὁδὸν Κυρίου,). He was going to make the paths straight (εὐθείας ποιεῖτε τὰς τρίβους αὐτοῦ). Clearly, there was a connection between John the Baptist and Isaiah the prophet.
Eugene Finnegan Bible Project 