Here are several New Testament prophecies on the falling away from sound doctrine. Many in the churches would say that it is the church which is to fall away from sound doctrine. Or, they would try to avoid these prophecies on the falling away from sound doctrine. They might claim end time prophecy on the falling away is not part of the "essentials."
But the present day religious organizations fit the metaphor in Revelation 17 - "And there came one of the seven angels which had the seven vials, and talked with me, saying unto me, Come hither; I will shew unto thee the judgment of the great ***** that sitteth upon many waters..........And upon her forehead was a name written, MYSTERY, BABYLON THE GREAT, THE MOTHER OF HARLOTS AND ABOMINATIONS OF THE EARTH."
And if the tower of Babel is metaphoric for apostasy in religions, then the present day religious organization fits there too. The elect of God, the Body of Christ, the saints, the wheat in the parables of the sower in Matthew 13 are the ones not included in Mystery Babylon of revelation 17 or the tower of Babel.
II Thessalonians 2: 3 says "Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition;"
"Then said he, Unto what is the kingdom of God like? and whereunto shall I resemble it?
19. It is like a grain of mustard seed, which a man took, and cast into his garden; and it grew, and waxed a great tree; and the fowls of the air lodged in the branches of it.
20. And again he said, Whereunto shall I liken the kingdom of God?
21. It is like leaven, which a woman took and hid in three measures of meal, till the whole was leavened." Luke 13: 18-21
In Luke 13: 18-21 the kingdom of God is predicted to become leavened, and the word till, or until, means that this process of leavening the kingdom of God goes on for some time until "the whole was leavened."
I Timothy 4: 1-2 says "Now the Spirit speaketh expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils; .Speaking lies in hypocrisy; having their conscience seared with ahot iron;"
II Timothy 4: 3-4 says "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; .And they shall turn away their ears from the truth, and shall beturned unto fables."
Matthew 24: 4-5: "And Jesus answered and said unto them, Take heed that no man deceive you.
5. For many shall come in my name, saying, I am Christ; and shall deceive many."
Matthew 24: 5 defines the false prophets, who teach a Christ but it is another Jesus and another Gospel (II Corinthians 11: 4). The spirit of anti-Christ is that spirit which preaches that Jesus Christ did not come in the flesh, that is, the spirit of anti-Christ denies that Jesus Christ is the Messiah (I John 2:18, I John 4: 3).
"And many false prophets shall rise, and shall deceive many. And because iniquity shall abound, the love of many shall wax cold. But he that shall endure unto the end, the same shall be saved." Matthew 24: 11-13
Then, II Peter 2: 1-3 says about the false prophets "But there were false prophets also among the people, even as there shall be false teachers among you, who privily shall bring in damnable heresies, even denying the Lord thatbought them, and bring upon themselves swift destruction.2. And many shall follow their pernicious ways; by reason of whom the way of truth shall be evil spoken of.3. And through covetousness shall they with feigned words make merchandise of you: whose judgment now of a long time lingereth not,and their damnation slumbereth not."
The second beast of Revelation 13: 11-18 represents the many false prophets of Matthew 24: 11, and this section is in metaphoric language. The text of Revelation 13: 12-18 describes the work of the false prophets, who in verse 12 are said to cause people to worship the first beast, whose deadly wound was healed. This beast is found in Revelation 13: 3 - one head of the first beast whose deadly wound was healed. The identity of the first beast is relealed in part in Daniel 7: 4-7, and the Little Horn which is the head of the beast in Revelation 13: 3.
In none of these texts does New Testament prophecy on the falling away from sound doctrine say that it is the church which falls away. However, Luke 13: 18-21 identifies that which is to be leavened as the kingdom of God. Christ says in Luke 17: 21 that the kingdom of God is within you, and in John 18: 36 he says "... My kingdom is not of this world: if my kingdom were of this world, then would my servants fight, that I should not be delivered to the Jews: "
The kingdom of God is to be leavened over a period of time, which corresponds to the falling away predicted in II Thessalonians 2: 3. The word ekklesia, which is consistently translated as church in the King James and in most recent Bibles, is not in the texts about the falling away, or about the false prophets who cause it.
And in the parables of the sower and of the sowing of seed in Matthew 13: 3-43 the ekklesia or church is not mentioned. In Verse 24 Christ says "The kingdom of heaven is likened unto a man which sowed good seed in his field." But in verse 26 tares were found in the field. Then in verse 38, when Christ is explaining the parables of sowing seed and reaping some tares among the wheat to his disciples he says "The field is the world; the good seed are the children of the kingdom; but the tares are the children of the wicked one." The word ekklesia or church is not found in these parables of the sowing of seeds. Yet the parables of the tares sprouting up among the wheat describes in metaphoric language the leavening of the kingdom of God in Luke 13: 18-21, the falling away of II Thessalonians 2: 3, and the two prophecies on departing from the faith and no longer enduring sound doctrine in I and II Timothy.
Ekklesia as a meeting, gathering, assembly or congregation is not a proper noun, meaning it is not unique like the elect of God, the Body of Christ, or the saints. The meeting does not fall away from sound doctrine. Because you would have to ask "Which meeting," and "Which meeting of what?" Christ uses kingdom of God in Luke 13: 18-21 to identify what is to be leavened and in Matthew 13: 24 he mentions the kingdom of heaven and that which is to bring forth both wheat and tares.