Please everyone try to be respectful. I know this question crosses denominational lines.
1 John 1:9
If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness.
Psalm 32:5 I acknowledged my sin to You, And my iniquity I did not hide; I said, I will confess my transgressions to the Lord; And You forgave the guilt of my sin.
"Why does this man speak that way? He is blaspheming; who can forgive sins but God alone?"
James 5
14 Is anyone among you sick? Then he must call for the elders of the church and they are to pray over him, anointing him with oil in the name of the Lord; 15 and the prayer offered in faith will restore the one who is sick, and the Lord will raise him up, and if he has committed sins, they will be forgiven him. 16 Therefore, confess your sins to one another, and pray for one another so that you may be healed. The effective prayer of a righteous man can accomplish much.
John 20
21 So Jesus said to them again, Peace be with you; as the Father has sent Me, I also send you. 22 And when He had said this, He breathed on them and *said to them, Receive the Holy Spirit. 23 If you forgive the sins of any, their sins have been forgiven them; if you retain the sins of any, they have been retained.
18 I also say to you that you are Peter, and upon this rock I will build My church; and the gates of Hades will not overpower it. 19 I will give you the keys of the kingdom of heaven; and whatever you bind on earth shall have been bound in heaven, and whatever you loose on earth shall have been loosed in heaven.
And Matt 18 - which talks about several things, and I'm debating how much to consider as being context, and why.
5 If your brother sins, go and show him his fault in private; if he listens to you, you have won your brother. 16 But if he does not listen to you, take one or two more with you, so that by the mouth of two or three witnesses every fact may be confirmed. 17 If he refuses to listen to them, tell it to the church; and if he refuses to listen even to the church, let him be to you as a Gentile and a tax collector. 18 Truly I say to you, whatever you bind on earth shall have been bound in heaven; and whatever you loose on earth shall have been loosed in heaven.
19 Again I say to you, that if two of you agree on earth about anything that they may ask, it shall be done for them by My Father who is in heaven. 20 For where two or three have gathered together in My name, I am there in their midst.
21 Then Peter came and said to Him, Lord, how often shall my brother sin against me and I forgive him? Up to seven times? 22 Jesus *said to him, I do not say to you, up to seven times, but up to seventy times seven.
Input?
What important, honest and soul searching questions you ask! God bless you, for starters. The scriptures you post tell us plenty. The OT was before Christ and His Apostles, who founded a Priesthood and a Church. The NT scriptures get a little bit more into the rubrics of the thing, since He appointed the 12, and the 12 (with their power to bind and loose), began the actual ministry of Christ's sacrament.
Some other NT scripture:
JOHN 20:
22 With that, he breathed on them, and said to them, Receive the Holy Spirit; 23 when you forgive mens sins, they are forgiven, when you hold them bound, they are held bound.
MARK 2: (MATTHEW 9:2-7)
5 And Jesus, seeing their faith, said to the palsied man, Son, thy sins are forgiven. 6 But there were some of the scribes sitting there, who reasoned in their minds, 7 Why does he speak so? He is talking blasphemously. Who can forgive sins but God, and God only? 8 Jesus knew at once, in his spirit, of these secret thoughts of theirs, and said to them, Why do you reason thus in your minds? 9 Which command is more lightly given, to say to the palsied man, Thy sins are forgiven, or to say, Rise up, take thy bed with thee, and walk?[1] 10 And now, to convince you that the Son of Man has authority to forgive sins while he is on earth (here he spoke to the palsied man): 11 I tell thee, rise up, take thy bed with thee, and go home.
in the Context of St. Peter: (binding and loosing AND the Keys to the Kingdom)
MATT 19:and I will give to thee the keys of the kingdom of heaven; and whatever thou shalt bind on earth shall be bound in heaven; and whatever thou shalt loose on earth shall be loosed in heaven.
Article on the "Power of the Keys" from the Catholic Encyclopedia:
CATHOLIC ENCYCLOPEDIA: Power of the Keys
More forgiving of sins - binding and loosing
Matthew 9:2-8; Luke 5:20; 7:47; Revelation 1:5
We see that confession to a Priest was always the practice from the early Church to present (From the Catholic Encyclopedia).
According to the Council of Trent, the consensus of all the Fathers always understood that by the words of Christ just cited, the power of forgiving and retaining sins was communicated to the Apostles and their lawful successors (Sess. XIV, c. i). It is therefore Catholic doctrine that the Church from the earliest times believed in the power to forgive sins as granted by Christ to the Apostles. Such a belief in fact was clearly inculcated by the words with which Christ granted the power, and it would have been inexplicable to the early Christians if any one who professed faith in Christ had questioned the existence of that power in the Church. But if, contrariwise, we suppose that no such belief existed from the beginning, we encounter a still greater difficulty: the first mention of that power would have been regarded as an innovation both needless and intolerable; it would have shown little practical wisdom on the part of those who were endeavouring to draw men to Christ; and it would have raised a protest or led to a schism which would certainly have gone on record as plainly at least as did early divisions on matters of less importance. But no such record is found; even those who sought to limit the power itself presupposed its existence, and their very attempt at limitation put them in opposition to the prevalent Catholic belief.
Turning now to evidence of a positive sort, we have to note that the statements of any Father or orthodox ecclesiastical writer regarding penance present not merely his own personal view, but the commonly accepted belief; and furthermore that the belief which they record was no novelty at the time, but was the traditional doctrine handed down by the regular teaching of the Church and embodied in her practice. In other words, each witness speaks for a past that reaches back to the beginning, even when he does not expressly appeal to tradition.
St. Augustine (d. 430) warns the faithful: "Let us not listen to those who deny that the Church of God has power to forgive all sins" (De agon. Christ., iii).
St. Ambrose (d. 397) rebukes the Novatianists who "professed to show reverence for the Lord by reserving to Him alone the power of forgiving sins. Greater wrong could not be done than what they do in seeking to rescind His commands and fling back the office He bestowed. . . . The Church obeys Him in both respects, by binding sin and by loosing it; for the Lord willed that for both the power should be equal" (On Penance I.2.6).
Again he teaches that this power was to be a function of the priesthood. "It seemed impossible that sins should be forgiven through penance; Christ granted this (power) to the Apostles and from the Apostles it has been transmitted to the office of priests" (On Penance II.2.12).
The power to forgive extends to all sins: "God makes no distinction; He promised mercy to all and to His priests He granted the authority to pardon without any exception" (On Penance I.3.10).
Against the same heretics St. Pacian, Bishop of Barcelona (d. 390), wrote to Sympronianus, one of their leaders: "This (forgiving sins), you say, only God can do. Quite true: but what He does through His priests is the doing of His own power" (Ep. I ad Sympron., 6 in P.L., XIII, 1057).
In the East during the same period we have the testimony of St. Cyril of Alexandria (d. 447): "Men filled with the spirit of God (i.e. priests) forgive sins in two ways, either by admitting to baptism those who are worthy or by pardoning the penitent children of the Church" (In Joan., 1, 12 in P.G., LXXIV, 722).
St. John Chrysostom (d. 407) after declaring that neither angels nor archangels have received such power, and after showing that earthly rulers can bind only the bodies of men, declares that the priest's power of forgiving sins "penetrates to the soul and reaches up to heaven". Wherefore, he concludes, "it were manifest folly to condemn so great a power without which we can neither obtain heaven nor come to the fulfillment of the promises. . . . Not only when they (the priests) regenerate us (baptism), but also after our new birth, they can forgive us our sins" (On the Priesthood III.5 sq.).
St. Athanasius (d. 373): "As the man whom the priest baptizes is enlightened by the grace of the Holy Ghost, so does he who in penance confesses his sins, receive through the priest forgiveness in virtue of the grace of Christ" (Frag. contra Novat. in P.G., XXVI, 1315).
It was made dogmatic by the Council of Trent:
CATHOLIC ENCYCLOPEDIA: The Sacrament of Penance
CATHOLIC ENCYCLOPEDIA: Council of Trent
A LOT of material to digest. Probably more that you asked for. Sorry about that. Lest anyone should disparage me for not answering off the cuff with MY belief on the matter, for what it's worth, I believe exactly what the Church teaches, so this IS my belief. Though my belief, were it to have been found at variance with the Church teaching, would be worthless anyway. I had much rather, personally learn doctrine from the scriptures, the Church, and her Fathers than all my friends "opinion" combined, including my own. This was and continues to be the very idea that led, (on a very rocky and windy road, from protestantism (Lutheranism) to secularism, to Buddhism, to new ageism(ugh.....I still scratch my head over this junk), back to Buddhism, back to protestantism (1st Baptist, then Methodist), and then FINALLY into the One, Holy, Catholic, and Apostolic Church, and the mystical body of Christ.
God bless. Keep asking the awesome questions, and read all the answers. Approach them all with prayer.