For if God. — The sentence has no proper conclusion. The third instance of God’s vengeance is so prolonged by the addition respecting Lot, that the apodosis is wanting, the writer in his eagerness having lost the thread of the construction. The three instances here are in chronological order (wanton angels, Flood, Sodom and Gomorrha), while those in Jude are not (unbelievers in the wilderness, impure angels, Sodom and Gomorrha). Both arrangements are natural — this as being chronological, that of St. Jude for reasons stated in the Notes there. (See on 2 Peter 2:5.)
The angels that sinned. — Better, the angels for their sin: it gives the reason why they were not spared, and points to some definite sin. What sin is meant? Not that which preceded the history of the human race, commonly called the fall of the angels — of that there is no record in the Old Testament; and, moreover, it affords no close analogy to the conduct of the false teachers. St. Jude is somewhat more explicit (Jude 1:6); he says it was for not keeping their own dignity — for deserting their proper home; and the reference, both there and here, is either to a common interpretation of Genesis 6:2 (that by “the sons of God” are meant “angels”), or, more probably, to distinct and frequent statements in the Book of Enoch, that certain angels sinned by having intercourse with women — e.g., Enoch vii. 1, 2; cv. 13 (Lawrence’s translation). Not improbably these false teachers made use of this book, and possibly of these passages, in their corrupt teaching. Hence St. Peter uses it as an argumentum ad hominem against them, and St. Jude, recognising the allusion, adopts it and makes it more plain; or both writers, knowing the Book of Enoch well, and calculating on their readers knowing it also, used it to illustrate their arguments and exhortations, just as St. Paul uses the Jewish belief of the rock following the Israelites. (See Note on 1 Corinthians 10:4.)
Cast them down to hell. — The Greek word occurs nowhere else, but its meaning is plain — to cast down to Tartarus; and though “Tartarus” occurs neither in the Old nor in the New Testament, it probably is the same as Gehenna. (See Note on Matthew 5:22.)
Into chains of darkness. — Critical reasons seem to require us to substitute dens, or caves, for “chains.” The Greek words for “chains” and for “caves” here are almost exactly alike; and “caves” may have been altered into “chains” in order to bring this passage into closer harmony with Jude 1:6, although the word used by St. Jude for “chains” is different. (See Note there.) If “chains of darkness” be retained, comp. Wis. 17:17. There still remains the doubt whether “into chains of darkness” should go with “delivered” or with “cast down into hell.” The former arrangement seems the better.