Prepare the way of the Lord. John the Baptist calls for repentance as he echoes the words of Isaiah 40, which also promise comfort.

Mark 1:1-8 (ESV)
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,’”
4 John appeared, baptizing in the wilderness and proclaiming a baptism of repentance for the forgiveness of sins. 5 And all the country of Judea and all Jerusalem were going out to him and were being baptized by him in the river Jordan, confessing their sins. 6 Now John was clothed with camel’s hair and wore a leather belt around his waist and ate locusts and wild honey. 7 And he preached, saying, “After me comes he who is mightier than I, the strap of whose sandals I am not worthy to stoop down and untie. 8 I have baptized you with water, but he will baptize you with the Holy Spirit.