https://en.wikipedia.org/wiki/Boiling_frog
The boiling frog is an anecdote describing a frog slowly being boiled alive. The premise is that if a frog is placed in boiling water, it will jump out, but if it is placed in cold water that is slowly heated, it will not perceive the danger and will be cooked to death. The story is often used as a metaphor for the inability or unwillingness of people to react to or be aware of threats that occur gradually.
This describes exactly what apostasy is: teachers who start out teaching truth then slowly introduce false doctrines so gradually that most of those that follow them will not discern the error. In part, this lack of discernment is due listening to their teachers who are twisting scripture that the followers believe is truth instead of reading scripture for their selves. Others love what the false teachers say because they have no love of the truth and love the ear tickling lies that say they do not have to obey Yeshua to follow Him. There are several teachers I used to recommend to others that have gone way over the deep end and are preaching false doctrines. Many churches have gone apostate and have bought into the lies of ihop / NAR, bethel-redding, hillsong, word faith, rick warren, and others. Some of the Messianic pastors I reccomened at one time are now preaching replacement theology, kabalah, and rabbinic Judaism instead of the faith of the early church. "christian kabalah" is starting to run rampant in mainstream "christianity" as well as the Messianic movement. This is gnosticism that has infiltrated the church since the beginning mixed with Jewish mysticism.
2 Timothy 3
1 This know also, that in the last days perilous times shall come.
2 For men shall be lovers of their own selves, covetous, boasters, proud, blasphemers, disobedient to parents, unthankful, unholy,
3 Without natural affection, trucebreakers, false accusers, incontinent, fierce, despisers of those that are good,
4 Traitors, heady, highminded, lovers of pleasures more than lovers of God;
5 Having a form of godliness, but denying the power thereof: from such turn away.
6 For of this sort are they which creep into houses, and lead captive silly women laden with sins, led away with divers lusts,
7 Ever learning, and never able to come to the knowledge of the truth.
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12 Yea, and all that will live godly in Christ Jesus shall suffer persecution.
13 But evil men and seducers shall wax worse and worse, deceiving, and being deceived.
2 Timothy 4
3 For the time will come when they will not endure sound doctrine; but after their own lusts shall they heap to themselves teachers, having itching ears;
4 And they shall turn away their ears from the truth, and shall be turned unto fables.
5 But watch thou in all things, endure afflictions, do the work of an evangelist, make full proof of thy ministry.
Wolves do not appear as wolves - they appear to be believers - they look like SHEEP or "pastors":
Matthew 7:15 Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves.
Messiah Yeshua warns that in the last days the deception would be so great that even the VERY elect could be deceived. Even so, many do not guard against the wolves and false teachers and, instead, listen to the false teachers for what little truth they may be teaching. Very few know enough do to lack of study and discernment to know what is truth and what is a lie AND Yahweh commanded us to not even listen to the false prophets because those false prophets are a test to see if we will listen to them or listen to Yahweh. Sometimes apologists listen to false teachers not to glean truth but to warn the sheep what the error is and to warn them to stay away from that error and that false teacher.
Matthew 24:24 For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect.
Jude 1
11 Woe unto them! for they have gone in the way of Cain, and ran greedily after the error of Balaam for reward, and perished in the gainsaying of Core.
12 These are spots in your feasts of charity, when they feast with you, feeding themselves without fear: clouds they are without water, carried about of winds; trees whose fruit withereth, without fruit, twice dead, plucked up by the roots;
13 Raging waves of the sea, foaming out their own shame; wandering stars, to whom is reserved the blackness of darkness for ever.
Deuteronomy 13
1 If there arise among you a prophet, or a dreamer of dreams, and giveth thee a sign or a wonder,
2 And the sign or the wonder come to pass, whereof he spake unto thee, saying, Let us go after other gods, which thou hast not known, and let us serve them;
3 Thou shalt not hearken unto the words of that prophet, or that dreamer of dreams: for the LORD your God proveth you, to know whether ye love the LORD your God with all your heart and with all your soul.
4 Ye shall walk after the LORD your God, and fear him, and keep his commandments, and obey his voice, and ye shall serve him, and cleave unto him.
A major error of OSAS (Once Saved Always Saved) is that those who claim to be "christians" do not believe listening to false teachers is a problem because "we are saved and there is nothing that can take away our salvation". These people are deceived because Messiah Yeshua says if they do not obey, then they are NOT His and He says to stay away from the false prophets. The apostle Paul says that the grafted in branches can be cut out again if they disobey.
Matthew 7
21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.
22 Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?
23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.
Romans 11
21 For if God spared not the natural branches, take heed lest he also spare not thee.
22 Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in his goodness: otherwise thou also shalt be cut off.
Revelation 2
20 Notwithstanding I have a few things against thee, because thou sufferest that woman Jezebel, which calleth herself a prophetess, to teach and to seduce my servants to commit fornication, and to eat things sacrificed unto idols.
21 And I gave her space to repent of her fornication; and she repented not.
22 Behold, I will cast her into a bed, and them that commit adultery with her into great tribulation, except they repent of their deeds.