The Confession of Sins in the Old Testament
In the Old Testament church God Himself establishes confession in the temple before the priest and cleansing from sin through the priest:
“And it shall be, when he is guilty in any of these matters, that he shall confess that he has sinned in that thing; and he shall bring his trespass offering to the LORD for his sin which he has committed, a female from the flock, a lamb or a kid of the goats as a sin offering. So the priest shall make atonement for him concerning his sin” (Lev. 5:5-6)
“He who covers his sins will not prosper, but whoever confesses and forsakes them will have mercy” (Prov. 28:13)
The Confession of Sins in the New Testament
The Priesthood Has the Authority to Forgive Sins
God brings about a change of the priesthood (more):
“For the priesthood being changed, of necessity there is also a change of the law” (Heb. 7:12)
He gives the new priesthood the authority to forgive sins:
“And I will give you the keys of the kingdom of heaven, and whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven” (Matt. 16:19)
“Assuredly, I say to you, whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven” (Matt. 18:18)
“And when He had said this, He breathed on them, and said to them, ‘Receive the Holy Spirit. If you forgive the sins of any, they are forgiven them; if you retain the sins of any, they are retained’” (John. 20:22-23)
Through the prayer of the priesthood sins are forgiven:
“Is anyone among you sick? Let him call for the elders of the church, and let them pray over him, anointing him with oil in the name of the Lord. And the prayer of faith will save the sick, and the Lord will raise him up. And if he has committed sins, he will be forgiven” (James. 5:14-15)
The priesthood has been appointed as overseers of the Church:
“he sent to Ephesus and called for the elders of the church. And when they had come to him, he said to them: <...> ‘Therefore take heed to yourselves and to all the flock, among which the Holy Spirit has made you overseers, to shepherd the church of God which He purchased with His own blood’” (Act. 20:17-18,28)
Confession Is Preserved in the Church
At the boundary of the Old and New Testaments people came to the prophet John the Baptist and likewise confessed their sins:
“John came baptizing in the wilderness and preaching a baptism of repentance for the remission of sins. Then all the land of Judea, and those from Jerusalem, went out to him and were all baptized by him in the Jordan River, confessing their sins” (Mark. 1:4-5)
Confession is preserved in the Church:
“And many who had believed came confessing and telling their deeds” (Act. 19:18)
Believers, After Acquiring the True Faith, Later Again Need the Forgiveness of New Sins
A true believer can turn his neighbor from a false path and thereby cover a multitude of his own sins:
“Brethren, if anyone among you wanders from the truth, and someone turns him back, let him know that he who turns a sinner from the error of his way will save a soul from death and cover a multitude of sins” (James. 5:19-20)
“Is anyone among you sick? Let him call for the elders of the church, and let them pray over him, anointing him with oil in the name of the Lord. And the prayer of faith will save the sick, and the Lord will raise him up. And if he has committed sins, he will be forgiven” (James. 5:14-15)
The Lord Does Not Reject Those Who Repent
God is always ready to accept the repentance of a sinner, however greatly he has sinned
“The sacrifices of God are a broken spirit, a broken and a contrite heart — these, O God, You will not despise” (Ps. 51:17)
“the one who comes to Me I will by no means cast out” (John. 6:37)