"Come to Me, all you who labor and are heavy laden, and I will give you rest. Take My yoke upon you and learn from Me, for I am gentle and lowly in heart, and you will find rest for your souls. For My yoke is easy and My burden is light." (Matthew 11:28-30)

The fundamental problem of all humanity is sin. Humans sin when they live in a way that is not aligned with and misses the original purpose of glorifying God's name. The cause of sin is the desire to live independently of God, leading to rebellion against Him. However, sin is detrimental to humans themselves as it subjects them to God's judgment. Sin is the cause of many problems and sufferings in the world. Depression is not always caused by sin since it is a complex bio-psycho-social-spiritual struggle. And we should not judge someone struggling with depression by claiming they harbor sin. Depression is not always due to sin. However, sin can cause depression and affect a person's physical condition.

Therefore, we need to reflect on the following questions:
If depression is influenced by sin, how do we resolve this fundamental problem that affects humans in heart, mind, emotion, and behavior? Can psychology solve this problem? The fundamental problem of sin is enmity with God. Therefore, reconciliation with God is necessary. The soul that is bound, shackled, and tormented by sin needs to be freed. How do we resolve the problem of sin against God?

God is Love. He is a God of compassion, patience, and abundant grace. God is a Person who loves humanity and wants to forgive human transgressions. God is love because He is a Person willing to offer forgiveness and grace. God is faithful to His covenant and full of merciful grace.
God's loving nature is one aspect of His Person. Another aspect is that He is just. A just God will judge every wrong act. God is also Holy, abhorring sin or violation of His holiness. Any violation against His holiness, consistent with His just nature, must be punished. Like a judge, God will judge those guilty before Him. And the punishment for sin is death. What humans need is forgiveness from God.

On one hand, God the source of grace loves and wishes to forgive all human transgressions. On the other, a just God must punish every transgression. God cannot compromise His just nature with His loving nature. God's justice must be manifested. And so must His love. Therefore, a sacrifice is needed that meets both God's justice and love. 
That's why God sent His Son, Jesus Christ, the Messiah, to die as a sacrifice for the atonement of human sins. Through Isaiah 53:10, we see that the Messiah "poured out His soul unto death". Out of love, Jesus Christ had to become human to be the atonement for sins. He was born into the world to sacrifice Himself and bear the sins of humanity.

To understand why Christ came, we must compare Christ and Adam. Adam, created in the image and likeness of God for His glory, was made to obey God's word. However, Adam failed and disobeyed God's word, falling into sin. As a result, all descendants of Adam are in sin. Adam represents humanity, and we are all under Adam. 

Christ, the true image of God, is the second Adam who came into the world. He came to obey God's word, which Adam failed to do. Adam sinned, but Christ did not. Adam failed to fulfill God's law, but Christ fulfilled it perfectly. And all who believe in Jesus Christ are in Him. In Jesus Christ, sinners are justified, not by their righteousness but by the righteousness that comes from Christ's obedience in fulfilling God's law.

Christ faithfully carried out God's will perfectly, even willing to suffer and die for sinners. He is the Perfect Sacrifice, without defect or blemish, the only One who can redeem human sin. The sinless One was made sin so that sinners might be justified. Sinful humans should have been punished, but Christ took that punishment. He died on the cross. However, the story does not end there. After being crucified, died, and buried, on the third day Jesus rose from death. He is God, powerful over death, so as His followers we need not fear death, which has always been a terror. Then, Jesus ascended into heaven to prepare a place for those who believe in Him. Therefore, the only solution to human sin is to believe in Jesus Christ, the Savior and Redeemer of human sins.

Those suffering from depression need to experience what is meant as total forgiveness from God. Depressed individuals wrestling with sin will recover if they experience total forgiveness from God. And God will forgive everyone who comes to Him.
"If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness." (1 John 1:9)

Forgiveness lifts the heavy burden of sin from the soul, and it also covers human sin. This forgiveness can only be granted through Jesus Christ. Through forgiveness, the Lord can restore the joy and rejoicing that sin has taken away.

"Purify me from my sins with hyssop, and I will be clean; wash me, and I will be whiter than snow! Let me hear joy and rejoicing; let the bones You have crushed rejoice again!" (Psalm 51)

Praise be to God who gives forgiveness of sins and relief to the human soul! But what is God's purpose in providing redemption for humans through Jesus Christ? The purpose is for the glory of God. Just as the ultimate purpose that God works in everything is for the glory of God, so too the purpose of Jesus Christ's redemption is for the glory of God.

Remember, when Jesus was born, the angels exclaimed:
"Glory to God in the highest, and on earth peace among those with whom He is pleased." (Luke 2:14).

The Bible also explains that Christ's coming into the world is to bring glory to God:
"Who, being in very nature God, did not consider equality with God something to be used to his own advantage; rather, he made himself nothing by taking the very nature of a servant, being made in human likeness. And being found in appearance as a man, he humbled himself by becoming obedient to death—even death on a cross! Therefore God exalted him to the highest place and gave him the name that is above every name, that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue acknowledge that Jesus Christ is Lord, to the glory of God the Father." (Philippians 2:6-11)

The purpose of human redemption in Christ is for the praise of the Lord, as stated in Ephesians 1:3-6:
"Praise be to the God and Father of our Lord Jesus Christ, who has blessed us in the heavenly realms with every spiritual blessing in Christ. For he chose us in him before the creation of the world to be holy and blameless in his sight. In love he predestined us for adoption to sonship through Jesus Christ, in accordance with his pleasure and will—to the praise of his glorious grace, which he has freely given us in the One he loves."

That is why, when believers are saved in the Lord Jesus Christ, the name of God the Father is glorified. Fanny Crosby wrote the hymn "To God Be the Glory" to describe this.

To God be the glory, great things He has done;
So loved He the world that He gave us His Son,
Who yielded His life an atonement for sin,
And opened the life gate that all may go in.

Refrain

Praise the Lord, praise the Lord,
Let the earth hear His voice!
Praise the Lord, praise the Lord,
Let the people rejoice!
O come to the Father, through Jesus the Son,
And give Him the glory, great things He has done.
2.
O perfect redemption, the purchase of blood,
To every believer the promise of God;
The vilest offender who truly believes,
That moment from Jesus a pardon receives.

Refrain
3.
Great things He has taught us, great things He has done,
And great our rejoicing through Jesus the Son;
But purer, and higher, and greater will be
Our wonder, our transport, when Jesus we see.

Refrain

("To God Be the Glory"; Fanny J. Crosby. Music: William H. Doane)