Isaiah 40:3-4

Isaiah announced that someone was calling out to prepare a highway in the desert, because the Lord was coming to His people’s aid (cf. Matthew 3:3; Mark 1:3; Luke 3:4; John 1:23; John 3:30). It was customary to construct processional avenues for approaching dignitaries and for idols carried in parade. The wilderness and desert represent the barren waste of Babylon where God’s people dwelt, complete with obstacles and impediments to overcome, and through which He would come to them with refreshment, as He did formerly at Mount Sinai. The idea is that He was certainly coming and His people should prepare for His appearing.