The answer is: Isaiah

Isa 40:3

In the Gospel of Mark, the first prophet called upon is none other than Isaiah, which adds significant historical weight to Jesus' ministry. Mark kicks off his Gospel by referencing Isaiah, showing how the prophecies about the coming Messiah were meant to set the stage for the great works ahead. Isaiah 40:3 specifically speaks of a "voice of one crying in the wilderness"—a clear reference to John the Baptist, who functions as that herald, preparing the way for Jesus.

This linkage is no light hand wave; it ties Jesus’ life and ministry right into the fabric of Jewish prophecy, spotlighting how God prepared humanity for this monumental moment through generations of prophecy. Speaking of preparation, did you know that "wilderness" in biblical terms is more than just a barren landscape? It often signifies a place of spiritual transformation, where divine encounters occur. Think of wilderness adventures throughout the Bible: Moses had his encounter with God in the burning bush there, and Jesus himself retreated to the wilderness to face temptation.

Mark crafts this with intentionality, as the wilderness leads to revelation. Readers are invited not just to see the timing of Jesus’ arrival in the Messiah’s lineage, but to feel the urgency and adventure of following this prophetic path through rugged figurative terrain. As readers, we hum along with that ancient expectation, eager for fulfillment in the person of Jesus.