Three Methods

Catholics teach 3 methods of receiving doctrine in the church, but they aren't really compatible.

1. Oral traditions not written in scripture.

2. Scripture.

3. Doctrines later defined in church councils by gifts of the Holy Spirit.

In their view the church grew in understanding of some doctrines as time passed and as the Holy Spirit worked through certain members. Thus they were given powers to interpret tradition and interpret scripture.

Of course we know that three gifts were meant to cease.

1Co 13:10  But when that which is perfect is come, then that which is in part shall be done away. 1Co 13:9  For we know in part, and we prophesy in part. 1Co 13:8  Charity never faileth: but whether there be prophecies, they shall fail; whether there be tongues, they shall cease; whether there be knowledge, it shall vanish away.

One way to know false prophets is simply seeing if their prophecies failed, or if their interpretations were later proven false.

I think an example would be the Church's interpretation of Polycarp, that he was baptized as a baby, but a later discovery called the Harris fragment showed him to be around 18 when baptized. The church's position and teaching proven to be false.

Victorinus, an early Catholic interpreted the Revelation of John in this light.

3. “Seven thunders uttered their voices.”] The seven thunders uttering their voices signify the Holy Spirit of sevenfold power, who through the prophets announced all things to come, and by His voice John gave his testimony in the world; but because he says that he was about to write the things which the thunders had uttered, that is, whatever things had been obscure in the announcements of the Old Testament; he is forbidden to write them, but he was charged to leave them sealed, because he is an apostle, nor was it fitting that the grace of the subsequent stage should be given in the first. “The time,” says he, “is at hand.”[1] For the apostles, by powers, by signs, by portents, and by mighty works, have overcome unbelief. After them there is now given to the same completed Churches the comfort of having the prophetic Scriptures subsequently interpreted, for I said that after the apostles there would be interpreting prophets.  

For the apostle says: “And he placed in the Church indeed, first, apostles; secondly, prophets; thirdly, teachers,”[2] and the rest. And in another place he says: “Let the prophets speak two or three, and let the others judge.”[3] And he says: “Every woman that prayeth or prophesieth with her head uncovered, dishonoureth her head.”[4] And when he says, “Let the prophets speak two or three, and let the others judge,” he is not speaking in respect of the Catholic prophecy of things unheard and unknown, but of things both announced and known. But let them judge whether or not the interpretation is consistent with the testimonies of the prophetic utterance.[5] It is plain, therefore, that to John, armed as he was with superior virtue, this was not necessary, although the body of Christ, which is the Church, adorned with His members, ought to respond to its position.  

Thus Victorinus is likely a false teacher. Notice that he quotes New Testament passages concerning prophets before the scriptures to those cities were written. There were already prophets in Corinth before Paul's letter there was written. Thus, the prophets there were not interpreting his letter. Paul's letter was written to regulate some of their sins in applying spiritual gifts. They were not interpreting New Testament scriptures since they were not written yet. They could be interpreting Old Testament prophecies but we can't prove it since none of their works were preserved.

It is likely they were teaching the life of Christ via prophetic gifts. This is clear from Ephesians 4 where gifts led them to an understanding of Jesus,

Eph 4:13  Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ:

Also the foundation of the Church includes Apostles and Prophets, the completed church was built upon both. Victorinus sees the Apostles building the church while prophets are designed for a later work of interpretation.

The term interpreting prophets isn't taught in the New Testament. The usage of interpretation. are mostly concerning languages. Peter says scripture is of no private interpretation. Peter is speaking of delivery of scripture and not the interpretation of it.

2Pe 1:19  We have also a more sure word of prophecy; whereunto ye do well that ye take heed, as unto a light that shineth in a dark place, until the day dawn, and the day star arise in your hearts:

2Pe 1:20  Knowing this first, that no prophecy of the scripture is of any private interpretation.

2Pe 1:21  For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost.

Peter is saying delivery of scripture did not include interpretive rights, scripture says what it says, no more and no less.

Keep in mind a later Pope deemed Victorinus' writings to be apocrapha, not based upon the above, but because he was a miiianiarist believing in a thousand year reign.

Victorinus writings are enough to establish the belief in interpreting prophets in 270 AD. Thus different groups were using this idea to take liberties in interpreting scripture.