Isa 40:3,4 The voice of him that crieth in the wilderness, Prepare ye the way of the LORD, make straight in the desert a highway for our God. Every valley shall be exalted, and every mountain and hill shall be made low: and the crooked shall be made straight, and the rough places plain:
The place where the Lord desires to dwell is in our hearts. Let them build me a sanctuary that I may dwell among them Ex 25:8. The true sanctuary where God wants to dwell is in our hearts. 1 Cor 6:19 For the Kingdom of God is within us. Luke 17:21.
The voice that comes to us and cries in the wilderness is the Spirit of Christ that continues to seek His lost children crying where are you my dear ones? We are in the wilderness - the dry and desolate place because the law of the Lord is not naturally our delight Ps 1:2 and our minds are naturally against the law Rom 8:7. Therefore we are not planted by the rivers of water Ps 1:3 and we are not like a well watered garden.
When the Spirit of Christ comes to us, He restores our true identity as children of God, sets us free from the lie that we have our own power, which then allows us to be reconnected to our Father and allows the Spirit of Christ to cry in us, Abba Father! Christ is allowed in because the mountains of pride have been cast down and the valleys of worthlessness have been exalted and we can then allow the chastening of the Lord and have our hearts turned back to Him!
Indeed God's people are comforted by the voice crying in the wilderness make straight in the desert a highway for our God.