2 Peter 1:12

Wherefore I shall be ready always to put you in remembrance of these things, though ye know them, and are established in the truth which is with you.

This and the next three verses deal with Peter's purpose in writing this letter, giving glimpses of vital Christian principles at the same time. As Barclay noted, "Peter here says that his people already possess the truth and are established in it."<39b> As noted also in 1John, the apostles did not view the Christian community as an inquiring band seeking to know what the truth is, but as a confident, vibrant community in full possession and enjoyment of it.

Remembrance of those things ... It is a mistake to view this as a reference restricted to what Peter had already written to those Christians; it is rather a citation of the entire corpus of Christian truth in which they were already established, not merely by Peter's preaching and writing alone, but by that of all the apostles of Christ.

Also, there is the principle in view here that requires Christian teachers to keep reminding the saints of truth they already know. As Jesus said, "Go tell John again!" (Matthew 11:4).