18. mockers—In the parallel, 2Pe 3:3, the same Greek is translated, "scoffers." The word is found nowhere else in the New Testament. How Alford can deny that 2Pe 3:2, 3 is referred to (at least in part), I cannot imagine, seeing that Jude quotes the very words of Peter as the words which the apostles used to speak to his (Jude's) readers.
walk after their own ungodly lusts—literally, "after (according to) their own lusts of ungodliness."