What was Peter talking about in II Peter 3:16 when he said that the ignorant and unstable would twist scriptures to their destruction?
"And consider that the longsuffering of our Lord is salvation--as also our beloved brother Paul, according to the wisdom given to him, has written to you, as also in all his epistles, speaking in them of these things, in which are some things hard to understand, which untaught and unstable people twist to their own destruction, as they do also the rest of the Scriptures" (II Peter 3:15-16).
"Untaught" translates the Greek word amathes, which refers to someone who is ignorant about a matter because he has never learned the subject.
"Unstable" translates the Greek word asteriktos, which refers to someone who can't make up their mind about a matter. They get swayed by every latest fad. "That we should no longer be children, tossed to and fro and carried about with every wind of doctrine, by the trickery of men, in the cunning craftiness of deceitful plotting" (Ephesians 4:14).
What Peter is saying is that everything in the Bible is not easy to understand. There are sections that are difficult. Often people who have little to no knowledge of the Bible will use the harder passages as proof of their claims, not realizing they are taking the passage out of its context. Others don't try to learn what God is teaching, but rather grab passages as proof-text for their favorite ideas. Examples of both of these are beliefs justified by pulling out obscure statements from Revelation or one the Old Testament prophets. No consideration is given as to what the book and the prophecy is really about.
Paul tackles some difficult subjects in his letters. His logic at times is sophisticated. But rather than studying Paul's arguments and understanding what he is saying, some find choice phrases that they pull out to claim things Paul never said. As an example, people will pull Romans 4:1-5 where Paul argues we cannot earn our salvation and then say that baptism would be a work to earn salvation; therefore, baptism is not necessary. But the conclusion cannot be correct because in the same book, just two chapters later, Paul argues that we cannot live in sin because all Christians were freed from sin through baptism (Romans 6:1-7). Still people get away with ignoring Romans 6 because their audience is ignorant of the Scriptures and are easily swayed.
"Beware lest anyone cheat you through philosophy and empty deceit, according to the tradition of men, according to the basic principles of the world, and not according to Christ" (Colossians 2:8).
Knowledge of the Scriptures that comes from reading and studying is the way to prevent being taken in by false doctrine.