You must have used a catholic interpretation of that passege. The problem with it is the translators are slanted.
2Pe 1:20 (KJV) Knowing this first, that no prophecy of the scripture is of any private interpretation.
2Pe 1:20 (NKJV) knowing this first, that no prophecy of Scripture is of any private interpretation,
2Pe 1:20 (MKJV) knowing this first, that no prophecy of the Scripture came into being of [its] own private interpretation.
2Pe 1:20 (ASV) knowing this first, that no prophecy of scripture is of private interpretation.
2Pe 1:20 (YLT) this first knowing, that no prophecy of the Writing doth come of private exposition,
2Pe 1:20 (BBE) Being conscious in the first place that no man by himself may give a special sense to the words of the prophets.
2Pe 1:20 (DBY) knowing this first, that [the scope of] no prophecy of scripture is had from its own particular interpretation,
2Pe 1:20 (RSV) First of all you must understand this, that no prophecy of scripture is a matter of one’s own interpretation,
2Pe 1:20 (WEB) knowing this first, that no prophecy of Scripture is of private interpretation.
2Pe 1:20 (MNT) But first be assured of this–that no prophecy of Scripture is of private interpretation.
2Pe 1:20 (TCNT) But first be assured of this:–There is no prophetic teaching found in Scripture that can be interpreted by man’s unaided reason;
2Pe 1:20 (WNT) But, above all, remember that no prophecy in Scripture will be found to have come from the prophet’s own prompting;