BUT FALSE PROPHETS ALSO AROSE AMONG THE PEOPLE: Egenonto (3PAMI) de kai pseudoprophetai en to lao: (Dt 13:1-2; 13:3 1Ki 18:19-22; 22:6; Neh 6:12-14; Isa 9:15; 56:10,11; Jer 6:13, Jer 14:13-15; 23:16,17,25-32; [Read esp Jer 23:9-32] Jer 27:14,15; 28:15-17; 29:8,9; 29:31,32 37:19; La 2:14; Eze 13:3-18; Hos 9:8; Mic 2:11; 3:5,11; Zech 13:3,4; Mt 7:15; Lu 6:26; Ro 16:18) (Torrey's Topic "False Prophets") (See the book of Jude for parallel on false teachers)

BUT (de) draws a dramatic contrast between God's true prophets who under the influence of Holy Spirit wrote the inerrant OT Scriptures (see note 2 Peter 1:21) and the pernicious pseudo prophets who were nicely summed up by the true prophet Jeremiah  (Lamentations 2:14)

Your prophets have seen for you false and foolish visions & they have not exposed your iniquity so as to restore you from captivity, but they have seen for you false and misleading oracles."

Note that their teaching failed to bring about holiness and freedom as Peter amplifies in the remainder of this chapter. Notice also their effect on those they deceive

The prophets prophesy falsely, & the priests rule on their own authority & My people love it so!..." (Jer 5:31)

How to Discern a False Prophet
Deuteronomy 13:1-5, 18:20-22

"If a prophet or a dreamer of dreams arises among you and gives you a sign or a wonder, and the sign or the wonder comes true, concerning which he spoke to you, saying, 'Let us go after other gods whom you have not known and let us serve them,' you shall not listen to the words of that prophet or that dreamer of dreams; for the LORD your God is testing you to find out if you love the LORD your God with all your heart and with all your soul. "You shall follow the LORD your God and fear Him; and you shall keep His commandments, listen to His voice, serve Him, and cling to Him. But that prophet or that dreamer of dreams shall be put to death, because he has counseled rebellion against the LORD your God who brought you from the land of Egypt and redeemed you from the house of slavery, to seduce you from the way in which the LORD your God commanded you to walk. So you shall purge the evil from among you. (Deut 13:1-5)

But the prophet who speaks a word presumptuously in My name which I have not commanded him to speak, or which he speaks in the name of other gods, that prophet shall die. "You may say in your heart, 'How will we know the word which the LORD has not spoken?' "When a prophet speaks in the name of the LORD, if the thing does not come about or come true, that is the thing which the LORD has not spoken. The prophet has spoken it presumptuously; you shall not be afraid of him' (Deut 18:20-22)

False prophets (5578) (pseudoprophetes) are men who falsely claim to be prophets of God and/or who prophesy falsely. They utter falsehoods under the name of divine prophecies. Such men falsely assume the work of a prophet when pretending to foretell things to come (Mt. 24:11, 24) or they teach false doctrines in the name of God (Matthew 7:15 [note], Lu 6:26, Acts 13:6, 2Cor 11:13, 1Jn 4:1; Revelation 16:13 [note]; Revelation 19:20 [note], used in Septuagint of Jer 6:13) Wherever important truth is at stake these counterfeits will offer their wares. In the Old Testament men claimed to speak from God when he had not sent them (Dt 18:20) Satan’s counterfeits with their insidious activities have always been present and will be especially prevalent during the time just before Jesus makes His triumphant return (Mt. 24:11, 24). Peter warns the saints stabilized by the truth in Chapter 1 to be alert to the false in Chapter 2.

Arthur Pink says

False prophets are to be found in the circles of the most orthodox, and they pretend to have a fervent love for souls, yet they fatally delude multitudes concerning the way of salvation. The pulpit, platform, and pamphlet hucksters have wantonly lowered the standard of divine holiness and so adulterated the Gospel in order to make it palatable to the carnal mind.”

John Piper

Chapter one is mainly an encouragement to avail ourselves of God's power to lead lives of godliness and love. Chapter two is mainly a warning against the destruction that will befall those who don't avail themselves of this power. If chapter one is the carrot, chapter two is the crack of the whip over our heads. There are no commands, no admonitions, no imperatives in chapter two; just pure, terrifying description of what will happen to those who fall prey to the false teachers in the church." (See full sermon Destruction Is not Sleeping)

Among the people (en to lao) refers to these false prophets arising in Israel as distinct from the Gentile world. Where God's truth is presence the counterfeit is not far behind. 

Hiebert quoting Anstadt observes that

The transition to this new subject is natural. "When the fortifications have been built, and the armor has been put on, and the weapons have been provided, then it is time to meet the enemy (ref)

JUST AS THERE WILL ALSO BE FALSE TEACHERS AMONG YOU: os kai en humin esontai (3PFMI) pseudodidaskaloi: (Mt 24:5,11,24; Mk 13:22; Lu 21:8; Acts 20:29,30; 1Cor 11:19; 2Cor 11:13-14; 2Cor 11:15 Gal 2:4, Gal 4:17; Eph 4:14; Col 2:8; 2:18; 2Thes 2:3-12; 1Ti 4:1-3; 2Ti 3:1-9; 4:3; Titus 1:11; 1Jn 2:18; 2:19  2:26 4:1; Jude 1:18; Rev 2:9; 13:14)

False Teachers (5572) (pseudodidaskalos from pseudes = untrue, deceitful, lying, wicked + didaskalos = Instructor, master, teacher = one who provides instruction) means literally false teachers or in this context those who parade themselves as Christian teachers, pastors, evangelists, etc, but who teach false doctrine. They are the antithesis of the apostles, teaching a false message of human invention rather than the apostolic message based on divinely inspired words. The root word didasko is interesting because it means to teach so as to shape the will of the one being taught by the content of taught.

As Peter illustrates in this chapter, this is exactly the modus operandi of these evil men who traffic in lies and deceit just like their father the devil (Jn 8:44). They use deadly doctrines to shape the will of the unsuspecting "sheep". The term for false teachers in unique to Peter and could refer to either those whose claim to be teachers is false because they have not been authorized as teachers in the Church or it could refer to those who were teaching what is false or perverse. Probably the term encompasses both ideas. The context suggest that they do not claim to present a new revelation from God (like a false prophet might do) but rather offer their teachings as accredited and authentic truth.

W. A. Criswell defines a "false teacher" as...

a suave, affable, personable, scholarly man who claims to be the friend of Christ. He preaches in the pulpit, he writes learned books, he publishes articles in the religious magazines. He attacks Christianity from within. He makes the church and the school a lodging place for every unclean and hateful bird. He leavens the meal with the doctrine of the Sadducees." (Criswell, W A. Believer's Study Bible: New King James Version. 1991. Thomas Nelson)

Among you (en humin) is more literally "in your midst" which clearly indicates these deceivers will infiltrate and intermingle with God's saints. The point is clear "among" indicates this is an "inside" job so to speak, just as Paul had warned the Ephesian elders would occur upon his departure.

MacDonald adds that

These false teachers take their place inside the church. They pose as ministers of the gospel. This is what makes the peril so great. If they came right out and said they were atheists or agnostics, people would be on guard. But they are masters of deception. They carry the Bible and use orthodox expressions —though using them to mean something entirely different. The president of a liberal theological seminary acknowledged the strategy as follows: '"Churches often change convictions without formally renouncing views to which they were previously committed, and their theologians usually find ways of preserving continuity with the past through re-interpretations. (MacDonald, W & Farstad, A. Believer's Bible Commentary: Thomas Nelson or Logos)

Paul gives a similar warning to the elders of the church at Ephesus, declaring...

For I did not shrink from declaring to you the whole purpose of God. Be on guard for yourselves and for all the flock, among which the Holy Spirit has made you overseers, to shepherd the church of God which He purchased with His own blood. I know that after my departure savage wolves will come in among you, not sparing the flock & from among your own selves men will arise, speaking perverse things, to draw away the disciples after them. Therefore be on the alert, remembering that night and day for a period of three years I did not cease to admonish each one with tears. And now I commend you to God and to the word of His grace, which is able to build you up and to give you the inheritance among all those who are sanctified. (Acts 20:27-32)

Daniel Defoe (of Robinson Crusoe fame) wrote

Whenever God erects a house of prayer, the Devil always builds a chapel there.

The point is that whenever the true work of God is found it is not long before satanic counterfeits began to infiltrate.

WHO WILL SECRETLY INTRODUCE: hoitines pareisaxousin (3PFAI):

Secretly introduce (3919) (pareisago from pará = unto or at the side of + eiságo = bring in, introduce) means to bring in by the side of (secretly and craftily), introduce surreptitiously (the root derivation of surreptitious means to "secretly snatch") or bring in under false pretenses. The metaphor (picture) is of spies or traitors stealthily introducing themselves into an enemy’s camp.

Lenski says that the full force of the verb means to bring in

sneakingly, covertly, so that unwary, simple people will not note what these teachers are bringing in.

These false teachers will present a clever, even catchy attractive message in which they will secretly introduce error alongside of the truth. The majority of their message is orthodox but the small percentage of doctrinal "poison" is enough to bring about destruction of souls.

Calvin adds a picturesque thought that these men

creep in by oblique turnings, as through burrows under ground.

Paul used the related noun form of pareisago (pareisaktos) when he warned the Galatian church about the

false brethren secretly brought in (pareisaktos) who had sneaked in (pareiserchomai from para = alongside + eiserchomai = to enter) to spy out our liberty which we have in Christ Jesus, in order to bring us into bondage." (Gal 2:4) 

Note again the effect of false doctrine...bondage not freedom.

Jude had a similar warning

For certain persons have crept in unnoticed, (pareisduno from para = alongside + eisdúo = enter in) those who were long beforehand marked out for this condemnation, ungodly persons who turn the grace of our God into licentiousness and deny our only Master and Lord, Jesus Christ. (Jude 1:4)

DESTRUCTIVE HERESIES: haireseis apoleias :

Destructive heresies - Literally heresies of destruction, the product of the heresies being destruction.

Destructive (684) (apoleia from apo = marker of separation, away from + olethros = ruin, death but not annihilation) refers to destruction of persons, objects, or institutions. The "doctrine" of these false teachers is potentially deadly as pictured by this word (apoleia) which ultimately pictures separation from God, an utter, hopeless ruin & loss of well-being and all that gives worth to existence. Out of the 18 NT uses of apoleia 5 occur in this short epistle (2:1 twice; 2:3; 3:7,16) and refer primarily to eschatological (theology concerned with the final events in the history of the world) judgment which does not mean extinction but ruination, not loss of being but loss of well being.

Heresies (139) (hairesis from haireo = to choose or select) means primarily a choice so originally hairesis did not initially convey an evil connotation. The root word means to choose and so hairesis was used for a philosopher’s school of followers or for any band of people who chose to follow him because they shared his beliefs. Hairesis primarily meant a  choosing and then that which is chosen or an opinion with the implication that it is a deliberate self-chosen opinion. Because the views espoused were frequently substitutes for the truth, the term came to denote erroneous or heretical teachings.

Heresies then are self-designed religious lies which lead to division and faction (cf. 1Cor 11:19; Gal 5:20). The tragedy of life is that people who hold different views very often finish up by disliking, not each others’ views, but each other. It should be possible to differ with a man and yet remain friends.

These false teachers taught heresies of destruction forcing the unwary to make choices that led away from the Light and into Darkness, Death & Damnation.

Heresies came to mean sect, party like Pharisees or Sadducees. Promoting a party spirit in a church is one of the works of the flesh (Gal 5:20). Whenever a church member says to another member, “Are you on my side or the pastor’s side?” he is promoting a party spirit and causing division. A false teacher forces you to make a choice between his doctrines and the doctrines of the true Christian faith. These false teachers brought in their self-chosen teachings that altered the sound doctrinal foundation of Christianity and so threatened to destroy the body of Christ.

EVEN DENYING: kai...arnoumenoi (PMPMPN): (Torrey's Topic Denial of Christ) (Mt 10:33; Lu 12:9; Acts 3:13; 14; 2Ti 2:12,13; Jude 1:4; Rev 2:13; 3:8)

Denying  (720) (arneomai) (Click word study) means to say one does not know about or is in any way related to a person or event. The present tense indicates that this denial was not momentary but represents a continual repudiation of the claims of the Master upon them.

To deny carries idea of conscious, purposeful action of the will. These false teachers deny the Master and thus deny the deity of Jesus Christ, and if they do away with His deity they destroy the entire body of Christian truth for if Christ is not Who He claimed to be, there is no Christian faith.

Deny is a significant word coming from Peter for His Lord had forewarned him

Truly I say to you that this very night, before a rooster crows, you will deny Me three times." which is exactly what he did (Mt 26:34, 35,70, 75)  

Peter knew, by bitter repentance, what a fearful thing it is to deny the Lord (