Luke 21:34-36 is the basis for the anytime rapture view. I would also look at John 14:3 and Revelation 3:10-11.
The type of people who will leave Christianity in the great falling away are not posting at this site. Go look at some videos of Yusuf Estes on You Tube and listen to why he left Christianity to become a muslim, for example. One form of leaving Christianity.
Luke 21:36 and Revelation 3:10 doesn't necessitate a pre-tribulation rapture. God could answer a person's prayer to escape all these things by having them die before they happen. This is a Biblical principle (Isaiah 57:1) that happened in the Old Testament.
Isaiah 57:1-2
The righteous perishes,
And no man takes it to heart;
Merciful men are taken away,
While no one considers
That the righteous is taken away from evil.
2 He shall enter into peace;
They shall rest in their beds,
Each one walking in his uprightness.
It may be that the “early” deaths brought about by cancers, other diseases, and accidents or other means are in fact a blessing from the LORD. There are at least two instances where God told us this was the case: a male child of Jeroboam; and Ahab. First, let’s look at the male child of Jeroboam:
1 Kings 14:10–13 (NKJV)
10 therefore behold! I will bring disaster on the house of Jeroboam, and will cut off from Jeroboam every male in Israel, bond and free; I will take away the remnant of the house of Jeroboam, as one takes away refuse until it is all gone.
11 The dogs shall eat whoever belongs to Jeroboam and dies
in the city, and the birds of the air shall eat whoever dies in the field; for the Lord has spoken!” ’ 12 Arise therefore, go to your own house. When your feet enter the city, the child shall die. 13 And all Israel shall mourn for him and bury him, for he is the only one of Jeroboam who shall come to the grave, because in him there is found something good toward the Lord God of Israel in the house of Jeroboam.
Jeroboam’s young son died (1 Kings 14:17) according to the message spoken by the prophet; he was spared from being disgraced in death with his father and the rest of his father’s household (1 Kings 15:29-31).
Ahab king of Israel also greatly displeased the LORD because of his wickedness, and his house was cursed like the house of Jeroboam, such that the dogs and birds of the air should eat their dead bodies (1 Kings 21:24). Yet because Ahab humbled himself, God decided to wait until Ahab died to bring the punishment during the reign of his son.
1 Kings 21:28–29 (NKJV)
28 And the word of the Lord came to Elijah the Tishbite, saying, 29 “See how Ahab has humbled himself before Me? Because he has humbled himself before Me, I will not bring the calamity in
his days. In the days of his son I will bring the calamity on his house.”
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John 14:3 does not necessitate a pre-tribulation rapture. It just says Jesus will eventually return and make room for us to live with him. This will happen in the millennial reign (Revelation 20) as well as the new heavens and the new earth (our final destination) (Revelation 21).
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A great apostasy is predicted (2 Thessalonians 2:3, 2 Thessalonians 2:10-12). I don't believe that people on this site are incapable for a minute. If the government takes away our right to buy and sell without renouncing our salvation; if we cannot worship God freely; if we are threatened with beheading (as ISIS is doing to Christians in Iraq and Syria)... many will fall away. Especially if they assume beforehand that God would not put them through such suffering.
Look at Iraq and Syria's Christians today. They didn't get raptured.
For example, check out this video:
Matthew 24:9-13
9 “Then they will deliver you up to tribulation and kill you, and you will be hated by all nations for My name’s sake. 10
And then many will be offended, will betray one another, and will hate one another. 11 Then many false prophets will rise up and deceive many. 12 And because lawlessness will abound, the love of many will grow cold. 13 But he who endures to the end shall be saved.
In Matthew 24, Jesus also talks about many people who will be deceived by false Christs and false returns of Christ.
In Luke 18:1-8, Jesus implies that many will fall away before He returns because they grow impatient waiting for Him to avenge them.
In 2 Peter 3:3-10, the Bible prophesied that people will reject the clear teaching in the Bible about the beginning (God's creation, starting with water, and the worldwide flood) and finally they will reject the clear teaching about the end (the bodily return of Jesus).
In the parable of the virgins (Matthew 25), all are seeking the bridegroom but only half actually endure (their lamps lit and ready for the bridegroom's arrival).