tn Grk “knowing this [to be] foremost.” Τοῦτο πρῶτον (touto prōton) constitute the object and complement of γινώσκοντες (ginōskontes). The participle is dependent on the main verb in v. 19 (“you do well [if you pay attention]”), probably in a conditional usage. An alternative is to take it imperativally: “Above all, know this.” In this rendering, πρῶτον is functioning adverbially. Only here and 2 Pet 3:3 is τοῦτο πρῶτον found in the NT, making a decision more difficult.

tn The ὅτι (hoti) clause is appositional (“know this, that”). English usage can use the colon with the same force.

tn Verse 20 is variously interpreted. There are three key terms here that help decide both the interpretation and the translation. As well, the relation to v. 21 informs the meaning of this verse. (1) The term “comes about” (γίνεται [ginetai]) is often translated “is a matter” as in “is a matter of one’s own interpretation.” But the progressive force for this verb is far more common. (2) The adjective ἰδίας (idias) has been understood to mean (a) one’s own (i.e., the reader’s own), (b) its own (i.e., the particular prophecy’s own), or (c) the prophet’s own. Catholic scholarship has tended to see the reference to the reader (in the sense that no individual reader can understand scripture, but needs the interpretations handed down by the Church), while older Protestant scholarship has tended to see the reference to the individual passage being prophesied (and hence the Reformation doctrine of analogia fidei [analogy of faith], or scripture interpreting scripture). But neither of these views satisfactorily addresses the relationship of v. 20 to v. 21, nor do they do full justice to the meaning of γίνεται. (3) The meaning of ἐπίλυσις (epilusis) is difficult to determine, since it is a biblical hapax legomenon. Though it is sometimes used in the sense of interpretation in extra-biblical Greek, this is by no means a necessary sense. The basic idea of the word is unfolding, which can either indicate an explanation or a creation. It sometimes has the force of solution or even spell, both of which meanings could easily accommodate a prophetic utterance of some sort. Further, even the meaning explanation or interpretation easily fits a prophetic utterance, for prophets often, if not usually, explained visions and dreams. There is no instance of this word referring to the interpretation of scripture, however, suggesting that if interpretation is the meaning, it is the prophet’s interpretation of his own vision. (4) The γάρ (gar) at the beginning of v. 21 gives the basis for the truth of the proposition in v. 20. The connection that makes the most satisfactory sense is that prophets did not invent their own prophecies (v. 20), for their impulse for prophesying came from God (v. 21).

sn No prophecy of scripture ever comes about by the prophet’s own imagination. 2 Pet 1:20–21, then, form an inclusio with v. 16: The Christian’s faith and hope are not based on cleverly concocted fables but on the sure Word of God—one which the prophets, prompted by the Spirit of God, spoke. Peter’s point is the same as is found elsewhere in the NT, i.e., that human prophets did not originate the message, but they did convey it, using their own personalities in the process.