Isaiah 40:3
The voice of one crying in the wilderness:
“Prepare the way of the Lord;
Make straight in the desert
A highway for our God.

These words of Isaiah find their fulfillment in John the baptizer.
He came before the Lord Jesus proclaiming repentance because the kingdom of God was at hand.
Many came and he baptized them in the Jordan River.
Others asked if he was the Messiah or the prophet Elijah.
John answered them, saying, “I baptize with water, but there stands One among you whom you do not know. It is He who, coming after me, is preferred before me, whose sandal strap I am not worthy to loose.” John 1:26-27
The day came when Jesus showed up on the banks of the river and John proclaimed, “Behold! The Lamb of God who takes away the sin of the world! This is He of whom I said, ‘After me comes a Man who is preferred before me, for He was before me.’ I did not know Him; but that He should be revealed to Israel, therefore I came baptizing with water.” John 1:29-31

As Christians, we are that voice crying in the wilderness today – proclaiming and preparing for the return of the Lord, “Repent, for the kingdom of God is at hand!”