Hi. I'm a former Catholic and now non-denominational follower of Christ

[Cathode]

2 Timothy 3:15-16, And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus. All scripture [is] given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness: . . . .

It wasn’t the 27 New Testament Books Timothy was reading, they didn’t exist.

The deposit was the Apostolic Oral Tradition which is guarded by The Holy Spirit and handed on in Truth.

 

[Cathode]

Paul told Timothy to sell indulgences?
That was the straw of corruption that broke the camel's back for Luther and forced him to demand Rome return to Apostolic Teaching.

Rubbish. Corruption of some Italian clergy is no excuse to break from the Church.

The binding and loosing Authority has been granted by Christ to the Church to forgive and retain sin, let alone adjudicate smaller matters of indulgences.
Unlike Protestant churches which have no power to bind or loose anything, The Catholic Church has real power granted by Christ.

Protestants crowned Luther their new Apostle, with new revelation, but Luther is not an Apostle’s arse, he is the one the Apostles warn about, a wolf that scatters the flock.

We see the priests of the old covenant make sin offerings, and prescribe their indulgences as well.
In the new covenant, we see Christ grant real power to His Apostolic Priesthood.

Which of the ECFs mentioned this practice in their letters?

“Just as in the Old Testament the priest makes the leper clean or unclean, so in the New Testament the bishop and presbyter binds or looses not those who are innocent or guilty, but by reason of their office, when they have heard various kinds of sins, they know who is to be bound and who loosed.” Jerome, Commentary on Matthew, 3:16,19 (A.D. 398).

“Father who knowest the hearts of all grant upon this Thy servant whom Thou hast chosen for the episcopate to feed Thy holy flock and serve as Thine high priest, that he may minister blamelessly by night and day, that he may unceasingly behold and appropriate Thy countenance and offer to Thee the gifts of Thy holy Church. And that by the high priestly Spirit he may have authority to forgive sins…” Hippolytus, Apostolic Tradition, 3 (A.D. 215).

“The Pontifex Maximus–that is, the bishop of bishops–issues an edict: ‘I remit, to such as have discharged (the requirements of) repentance, the sins both of adultery and of fornication.'” Tertullian, Modesty, 1 (A.D. 220).

“Moreover, how much are they both greater in faith and better in their fear, who, although bound by no crime of sacrifice to idols or of certificate, yet, since they have even thought of such things, with grief and simplicity confess this very thing to God’s priests, and make the conscientious avowal, put off from them the load of their minds, and seek out the salutary medicine even for slight and moderate wounds, knowing that it is written, ‘God is not mocked.’ God cannot be mocked, nor deceived, nor deluded by any deceptive cunning. Yea, he sins the more, who, thinking that God is like man, believes that he evades the penalty of his crime if he has not openly admitted his crime…I entreat you, beloved brethren, that each one should confess his own sin, while he who has sinned is still in this world, while his confession may be received, while the satisfaction and remission made by the priests are pleasing to the Lord?” Cyprian, To the Lapsed, 28-29 (A.D. 251).

“It is necessary to confess our sins to those whom the dispensation of God’s mysteries is entrusted.” Basil, Rule Briefly Treated, 288 (A.D. 374).

“The Church holds fast its obedience on either side, by both retaining and remitting sin; heresy is on the one side cruel, and on the other disobedient; wishes to bind what it will not loosen, and will not loosen what it has bound, whereby it condemns itself by its own sentence. For the Lord willed that the power of binding and of loosing should be alike, and sanctioned each by a similar condition…Each is allowed to the Church, neither to heresy, for this power has been entrusted to priests alone. Rightly, therefore, does the Church claim it, which has true priests; heresy, which has not the priests of God, cannot claim it. And by not claiming this power heresy pronounces its own sentence, that not possessing priests it cannot claim priestly power. And so in their shameless obstinacy a shamefaced acknowledgment meets our view. Consider, too, the point that he who has received the Holy Ghost has also received the power of forgiving and of retaining sin. For thus it is written: ‘Receive the Holy Spirit: whosesoever sins ye forgive, they are forgiven unto them, and whosesoever sins ye retain, they are retained.’ So, then, he who has not received power to forgive sins has not received the Holy Spirit. The office of the priest is a gift of the Holy Spirit, and His right it is specially to forgive and to retain sins. How, then, can they claim His gift who distrust His power and His right?” Ambrose, Concerning Repentance, I:7-8 (A.D. 388).

 

[Cathode]

Which of the ECFs mentioned this practice in their letters?

The greatest preacher of the Early Church John Chrysostom tells us the power a priest possesses. I am talking regarding the forgiveness of sin itself, the lesser consideration is indulgences which is also their judgment.

“Priests have received a power which God has given neither to angels nor to archangels. It was said to them: ‘Whatsoever you shall bind on earth shall be bound in heaven; and whatsoever you shall loose, shall be loosed.’ Temporal rulers have indeed the power of binding; but they can only bind the body. Priests, in contrast, can bind with a bond which pertains to the soul itself and transcends the very heavens. Did [God] not give them all the powers of heaven? ‘Whose sins you shall forgive,’ he says, ‘they are forgiven them; whose sins you shall retain, they are retained.’ What greater power is there than this? The Father has given all judgment to the Son. And now I see the Son placing all this power in the hands of men [Matt. 10:40; John 20:21–23]. They are raised to this dignity as if they were already gathered up to heaven” (The Priesthood 3:5 [A.D. 387]). John Chrysostom.