3:3 first. “First” means “First of all,” or “of primary importance.” Compare II Peter 1:20. It is vitally important both to understand this key characteristic of the last days (that is, the denial of both creation and consummation), and also to know and practice the divinely inspired Scriptures.
3:3 last days. The context here is set in the last days. Although we must not set dates, these aspects of the last days are surely more characteristic of our own times than any time before us. At least, we are closer to the last days than anyone has ever been before! Thus Peter’s exhortation and analysis surely fits us better than anyone before us.
3:3 their own lusts. People of the last days, by and large, will be almost entirely motivated by self-interest, and will be unconcerned about God’s purposes, either for themselves or for the world as a whole. They will mock God’s Word. This word is used thirteen times in the New Testament, twelve of which speak of mocking Christ.