2 Peter 3:16, “as he does in all his letters when he speaks in them of these matters. There are some things in them that are hard to understand, which the ignorant and unstable twist to their own destruction, as they do the other Scriptures.”
The Apostles were Infallible in their teaching and writings.
All Catholics did is preserve those writings and the same interpretation of them, in Apostolic Tradition.
Apostolic Tradition is the Apostles interpretation of Scripture handed down.
Outside the ancient Apostles understanding of scripture is error, and in many cases spiritually fatal error.
Read all the Church Fathers, they were pathological about maintaining the same Apostolic understanding of Scripture and rejected any new interpretations of scripture.
Protestantism didn’t just reject the ancient Apostles interpretation of scripture they quickly rejected each other’s interpretations of scripture.
Through circumstance, history and heresy, Protestants today have been robbed of the Apostles interpretation of scripture.
Apostolic Tradition seems foreign, strange and pagan even, because private interpreters have poisoned them against the Fathers, and stolen their inheritance.
But for all the divine words, there is no need of allegory to grasp the meaning; what is necessary is study and understanding to know the meaning of each statement. We must have recourse to tradition, for all cannot be received from the divine Scriptures. That is why the holy Apostles handed down certain things in writings but others by traditions. As Paul said:” Just as I handed them on to you.”‘ Ephiphanius of Salamis, Panarion 61, 6 (A.D. 377).
“In answer to the objection that the doxology in the form ‘with the Spirit’ has no written authority, we maintain that if there is not other instance of that which is unwritten, then this must not be received. But if the great number of our mysteries are admitted into our constitution without written authority, then, in company with many others, let us receive this one. For I hold it apostolic to abide by the unwritten traditions. ‘I praise you,’ it is said, ‘that ye remember me in all things, and keep the ordinances as I have delivered them to you;’ and ‘Hold fast the traditions which ye have been taught whether by word, or our Epistle.’ One of these traditions is the practice which is now before us, which they who ordained from the beginning, rooted firmly in the churches, delivering it to their successors, and its use through long custom advances pace by pace with time.” Basil, Holy Spirit 71 (c. A.D. 370).