When Jesus gave His life on the cross for mankind, he paid the eternal debt of all the sins of the world, and the moment a man comes into Christ Jesus by believing in this sacrifice, His finished work (death, burial and resurrection of Jesus), that man receives the complete forgiveness of his sins from God, and thus, God declares him Righteous, he receives a right standing before God not because of what he did, but because of that which Christ accomplished for him.
Below are some Scriptural Verses that tells of God’s Forgiveness Of Sin
Matthew 26:28 KJV
[28] For this is my blood of the new testament, which is shed for many for the remission of sins.
Luke 24:47 KJV
[47] And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem.
Acts 5:31 KJV
[31] Him hath God exalted with his right hand to be a Prince and a Saviour, for to give repentance to Israel, and forgiveness of sins.
Acts 10:43 KJV
[43] All the prophets bear witness to Him that everyone who believes in Him receives forgiveness of sins through His name.
Act 13:38-39
[38]Be it known unto you therefore, men and brethren, that through this man is preached unto you the forgiveness of sins:
[39] And by him all that believe are justified from all things, from which ye could not be justified by the law of Moses.
Romans 3:24-25 KJV
[24] Being justified freely by his grace through the redemption that is in Christ Jesus:
[25] Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
Romans 4:7-8 KJV
[7] Saying, Blessed are they whose iniquities are forgiven, and whose sins are covered. [8] Blessed is the man to whom the Lord will not impute sin.
Ephesians 1:7 KJV
[7] In whom we have redemption through his blood, the forgiveness of sins, according to the riches of his grace;
Colossians 1:14 KJV
[14] In whom we have redemption through his blood, even the forgiveness of sins:
Hebrews 8:12 KJV
[12] For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more.
Isaiah 43:25
Good News Translation
And yet, I am the God who forgives your sins, and I do this because of who I am. I will not hold your sins against you.
Psalm 130:3-4
[3]If you, O LORD, should mark iniquities, O Lord, who could stand?
[4]But with you there is forgiveness, that you may be feared.
1 John 2:2 KJV
[2] And he is the propitiation for our sins: and not for ours only, but also for the sins of the whole world.
1 John 2:12 KJV
[12] I write unto you, little children, because your sins are forgiven you for his name’s sake.
1 John 4:10 KJV
[10] Herein is love, not that we loved God, but that he loved us, and sent his Son to be the propitiation for our sins.