The Bible is a massive book.
This may seem too obvious to be worth stating, but the truth is that these pages are full of history and prophecy and poetry make a very long book. It would be impossible to keep every idea in this book in the front of your mind. Anyone who has ever read a book of epic length (or a series of epic books!) knows that you forget or fail to notice certain details of the story. I’m not much for re-reading, personally, but I have many friends who love to read their favorite books over and over, remembering their favorite parts and discovering new ones.
Many people take a year or more just to read the Bible, but even after many years of study, readers find there is still more to learn inside this large book. When Peter writes his second letter, he rejoices that his readers are already “established in the truth” that they have (2 Peter 1:12), but he wants to continue to “stir them up by way of reminder” at every opportunity (2 Peter 1:13). Perhaps they have forgotten some of the things they need to know. This speaks to the importance of fellowshipping with other believers.
One of the reasons we must remain in fellowship with other believers is so that we can remind one another of gospel-truths we may have forgotten in our present circumstances. No one can keep all of the promises and warnings from Scripture in the front of his or her mind at all times. We need to remind others and be reminded.
Peter is prepared to remind his precious fellow believers, even though they “have obtained a faith of equal standing with ours” (2 Peter 1:1). This is not a matter of talking down to an inferior believer, but of encouraging a peer. It can be humbling to need reminders, but we must all take turns being the ones who remind and the ones who need reminders.
Peter knows that he will not be present “in the body” much longer (2 Peter 1:13) because Jesus has revealed to him “that the putting off of my body will be soon” (2 Peter 1:14). This letter is an opportunity to remind his fellow believers of what is true, but also to model for them how they are to encourage one another. Peter has no idea how long it will be until Jesus’ promised return, but he knows that after he departs, believers will need to “recall these things,” that is, the things he has seen with his eyes and heard with his ears (2 Peter 1:15).