2 Peter 2:1

But there were false prophets also among the people
As well as holy men of God, who gave out prophecies, by the inspiration and impulse of the Holy Spirit; that is, among the people of the Jews, God's professing people, whose God was the Lord, and who had chosen them to be a special and peculiar people, above all people of the earth; and had distinguished them by his favours from all others: among these, though the Syriac version reads "in the world", there were false prophets, who ran, and were not sent; and who prophesied, and the Lord spake not to them: of these there were many in Jeremiah's time, and in the times of Ezekiel; and in Ahab's time, besides the four hundred and fifty prophets of Baal, slain by Elijah, there were four hundred that called themselves the prophets of the Lord; among whom went forth a lying spirit, encouraging Ahab to go up to Ramoth Gilead, promising him prosperity and success; Zedekiah the son of Chenaanah, with whom Micaiah, the true prophet, had much contention, was at the head of them; and such there were among that people in all ages, until the times of Christ, and in his likewise; see ( Matthew 7:15 ) now from these, by an easy transition, the apostle proceeds to another part of his design in this epistle, to describe the characters of false teachers under the present dispensation, that saints may beware, and avoid their pernicious principles and practices:

even as there shall be false teachers among you;
which need not to be wondered at, or stumble any, it being no new or strange thing, but what was always more or less the case of the people of God. This is a prophecy of what should be, and agrees with the prediction of our Lord, ( Matthew 24:11 Matthew 24:24 ) and which regards not only the times immediately following, in which it had a remarkable fulfilment, for false teachers now began to arise, and appeared in great numbers in the age succeeding the apostles, but to all periods of time from hence, to the second coming of Christ; and these were to spring from, and be among such that bore the Christian name, and so regards not Mahometans and Deists; and it is to be observed, that the phrase is varied in this clause, and these are called not "prophets" but "teachers": because as prophecy was more peculiar to the former dispensation, so is teaching to the present:

who privily shall bring in damnable heresies:
errors in the fundamental doctrines of the Gospel; such as relate to a trinity of persons in the Godhead; and to the person of Christ, to his proper deity, distinct personality, eternal sonship, and real humanity; and to his office as Mediator, rejecting him as the true Messiah, and as the only Saviour of sinners; denying his sacrifice and satisfaction, and the imputation of his righteousness; and to the Holy Spirit, his deity, personality, and divine influences and operations: these are "damnable", or "destructive", or "heresies of destruction"; which lead to eternal destruction both those that introduce and propagate them, and those that embrace and profess them; for they remove, or attempt to remove, the foundation of eternal life and happiness: the manner in which these are usually introduced is "privily"; at unawares, secretly, under a disguise, and gradually, by little and little, and not at once, and openly; and which is the constant character and practice of such men, who lie in wait to deceive, creep into churches at unawares, and into houses privately; and insinuate their principles under specious pretences and appearances of truth, using the hidden things of dishonesty, walking in craftiness, handling the word of God deceitfully, and colouring things with false glosses and feigned words: and even denying the Lord that bought them; not the Lord Jesus Christ, but God the Father; for the word (kuriov) is not here used, which always is where Christ is spoken of as the Lord, but (despothv) ; and which is expressive of the power which masters have over their servants {i}, and which God has over all mankind; and wherever this word is elsewhere used, it is spoken of God the Father, whenever applied to a divine person, as in ( Luke 2:29 ) ( Acts 4:24 ) ( 2 Timothy 2:21 ) ( Revelation 6:10 ) and especially this appears to be the sense, from the parallel text in ( Jude 1:4 ) where the Lord God denied by those men is manifestly distinguished from our Lord Jesus Christ, and by whom these persons are said to be bought: the meaning is not that they were redeemed by the blood of Christ, for Christ is not intended; and besides, whenever redemption by Christ is spoken of, the price is usually mentioned, or some circumstance or another which fully determines the sense; see ( Acts 20:28 ) ( 1 Corinthians 6:20 ) ( 7:23 ) ( Ephesians 1:7 ) ( 1 Peter 1:18 1 Peter 1:19 ) ( Revelation 5:9 ) whereas here is not the least hint of anything of this kind: add to this, that such who are redeemed by Christ are the elect of God only, the people of Christ, his sheep and friends, and church, and who are never left to deny him so as to perish eternally; for could such be lost, or deceive, or be deceived finally and totally by damnable heresies, and bring on themselves swift destruction, Christ's purchase would be in vain, and the ransom price be paid for nought; but the word "bought" regards temporal mercies and deliverance, which these men enjoyed, and is used as an aggravation of their sin in denying the Lord; both by words, delivering out such tenets as are derogatory to the glory of the divine perfections, and which deny one or other of them, and of his purposes, providence, promises, and truths; and by works, turning the doctrine of the grace of God into lasciviousness, being disobedient and reprobate to every good work; that they should act this part against the Lord who had made them, and upheld them in their beings and took care of them in his providence, and had followed them with goodness and mercy all the days of their lives; just as Moses aggravates the ingratitude of the Jews in ( Deuteronomy 32:6 ) from whence this phrase is borrowed, and to which it manifestly refers: "do ye thus requite the Lord, O foolish people and unwise! is not he thy Father that hath bought thee? hath he not made thee, and established thee?" nor is this the only place the apostle refers to in this chapter, see ( 2 Peter 2:12 2 Peter 2:13 ) compared with ( Deuteronomy 32:5 ) and it is to be observed, that the persons he writes to were Jews, who were called the people the Lord had redeemed and purchased, ( Exodus 15:13 Exodus 15:16 ) and so were the first false teachers that rose up among them; and therefore this phrase is very applicable to them:

and bring upon themselves swift destruction;
either in this life, being suddenly cut off in the midst of their days, and by the immediate hand of God, as Arius and other heretics have been; or eternal damnation in the other, which their tenets lead unto, and which will swiftly come upon them when they are promising themselves peace and safety.