The beginning of the gospel of Jesus Christ, the Son of God. (2) As it is written in Isaiah the prophet, "Behold, I send my messenger before your face, who will prepare your way, (3) the voice of one crying in the wilderness: 'Prepare the way of the Lord, make his paths straight,'"
Expository thoughts
The Gospel According to Mark is a book of testimony that bears witness to Jesus the Messiah. Mark opened his gospel narrative with the Greek word for “beginning” (ἀρχή). The opening word ΑΡΧΗ resembles the LXX opening word in Hosea 1:2 ΑΡΧΗ. The Greek version of Hosea speaks of the beginning of the Lord’s word as it began to come to Hosea. Mark 1:1 speaks of the beginning of the gospel as it began to be made known, in fulfillment of the predictions made by the prophet Isaiah (see Isa. 40:9; 52:7; 60:6; 61:1). In Hosea, the beginning was the beginning of the history of new divine revelation as it came to him. Perhaps in Mark, then, the beginning here means the history of the beginning of new divine revelation as it came in and through Jesus Christ. Mark referenced the book of Isaiah, but quoted a combination of Malachi 3:1, Exodus 23:20 and Isaiah 40:3. Isaiah chapter 40 is an announcement of anticipated good news which would be realized after the period of Israel’s exile in Babylon. The opening words are, “Comfort, comfort my people, says your God” (Isa. 40:1). These gracious words anticipated the comforting good news that Jerusalem’s warfare had ended, her iniquity had been pardoned and the wrath of God had been more than satisfied by double payment for her sins (Isa. 40:2). A voice calls for the preparation of the Lord’s way in the desert wilderness (40:3). Malachi 3:1 is used in context of Isaiah 40:3 by building on the concept of a predicted messenger who would prepare the Lord’s way in the wilderness. Malachi was written at a later date than Isaiah, yet Malachi reiterates the promise of a forerunner who prepares the way for the Lord to come. Both quotations are linked to the idea as it was first presented by Moses in Exodus 23:20, where God warns the people of Israel that they must obey the voice of his angel (messenger) whom he will send before them to keep them in their way as they traversed the desert wilderness. In each of the passages just mentioned, the Lord’s way in the wilderness indicates God’s own presence to deliver His chosen people Israel. Mark seems to have traced the concept of the Lord’s forerunner/messenger from its development in the history of revelation up to the point of John. He seems to have understood these predictions to have had the ability to reach beyond the prophet’s own experience at the time of their writing, as well as beyond Israel’s experience in returning from Babylon, and to reach forward to describe the period of fulfillment when the good news would become evident. In other words, Mark understood Isaiah’s prophetic announcement of good news to have been fulfilled by Jesus the Messiah. The basic premise of Mark’s writing is this: God has fulfilled His promises of good news by sending Messiah Jesus, His Son. The beginning of this good news is the ministry work of John the Baptist, who signals its inauguration.