13  Now when the dragon saw that he had been cast to the earth, he persecuted the woman who gave birth to the male Child. 14  But the woman was given two wings of a great eagle, that she might fly into the wilderness to her place, where she is nourished for a time and times and half a time (three and a half years), from the presence of the serpent. 15  So the serpent spewed water out of his mouth like a flood after the woman, that he might cause her to be carried away by the flood. 16  But the earth helped the woman, and the earth opened its mouth and swallowed up the flood which the dragon had spewed out of his mouth. 17  And the dragon was enraged with the woman, and he went to make war with the rest of her offspring, who keep the commandments of God and have the testimony of Jesus Christ.

This part of scripture involves Satan (the dragon) persecuting the nation of Israel (the woman) and records that she will be helped supernaturally to flee to the wilderness to a place of safety prepared for her to be nourished for three and a half years. This means it will be fulfilled in the middle of the 7 year rule of the antichrist, because that is the time when the antichrist commits the abomination of desolation (sitting in the temple in Jerusalem and proclaiming himself to be God - 2 Thes. 2:3-4), for which Israel is commanded to flee to the mountains.

15  "Therefore when you see the 'abomination of desolation,' spoken of by Daniel the prophet, standing in the holy place" (whoever reads, let him understand), 16 "then let those who are in Judea flee to the mountains."

So we learn from the Book of Revelation that the mountains spoken of by Jesus are also known as the wilderness and they serve the purpose of a supernatural safe haven where the Israelites will be both safe and nourished until the end of the great tribulation. This begs the following question:
If the nation of Israel (,as many as heed the commandment to flee to the mountainous wilderness,) is guaranteed a place of safety in the mountainous wilderness from the persecution of the antichrist, which saints will he persecute? For it is written after this that he will be granted to him to make war with the saints and to overcome them (Rev. 13:7); and he will use the authority of Satan (the dragon) (Rev 13:4).
Verses 15-17 show that when Satan fails to destroy Israelites who flee to the wilderness, he will become enraged and will go to make war with the rest of her offspring, who keep the commandments of God and have the testimony of Jesus Christ. The rest of the offspring of the woman (Israel) refers to the church because:

• In this period Israel is not identified with having the testimony of Jesus Christ, given that, they are worshipping according to the way earlier prescribed by Moses - the abomination of desolation is immediately preceded by the antichrist violating his 7 year peace treaty by putting an end to the daily sacrifices (Daniel 9:27). Carrying out daily sacrifices evidences that they are not believers in Jesus Christ, the messiah, whose self sinless sacrifice puts an end to the need for the sacrifice of bulls, goats, etc., as practiced in the Old Testament (Hebrews 7:26-27, 10:18).
• Israel has run to their place of safety.
• The rest of her offspring Satan makes war with is the global church. The church is an offspring of Israel (the woman) in the sense that salvation was of the Jews and we gentiles were simply grafted in like a formerly wild tree when they rejected Christ (Romans 11:11-24; John 4:22).

The obvious conclusion is not only will the church be present during those times but that the great tribulation is custom made for the church. We must prepare mentally and spiritually for the coming tribulation and not continue under the illusion that we will be raptured before it comes. Just as Job was a candidate for tribulation resulting from the boasting of God to the devil about his faithfulness, and subsequently God allowed Satan to severely try and test his faith, Job being found to be pure as gold at the end of the process (Job 1 & 2), so also shall we, as many as will be alive, be during the great tribulation. The purpose of the great tribulation is made clear in the scriptures:

33  And those of the people who understand shall instruct many; yet for many days they shall fall by sword and flame, by captivity and plundering. 34  Now when they fall, they shall be aided with a little help; but many shall join with them by intrigue. 35  And some of those of understanding shall fall, to refine them, purify them, and make them white, until the time of the end; because it is still for the appointed time.

To the carnal mind, the devil will be winning when many saints are beheaded, burnt and have their possessions plundered but this light affliction, which is but for a moment, shall be working for them a far more exceeding and eternal weight of glory (2 Corinthians 4:17).
It should be equally appreciated that the great tribulation period is not a period of God's wrath as suggested by some scholars, but it is instead the period of the permitted wrath of the devil:
Woe to the inhabitants of the earth and the sea! For the devil has come down to you, having great wrath, because he knows that he has a short time. (Rev. 12:12).
And the dragon was enraged with the woman, and he went to make war with the rest of her offspring, who keep the commandments of God and have the testimony of Jesus Christ (Rev. 12:17).
The time of the wrath of God is after the seventh angel has blown his trumpet (the last trumpet, which causes rapture). This takes place when the seventh seal is opened (Rev. 7-11) following the appearance of Jesus Christ on the clouds, an event that happens when the 6th seal is opened (Rev. 6:12-17). See also 1 Corinthians 15:51; Revelation 10:5-7.

15  Then the seventh angel sounded: And there were loud voices in heaven, saying, "The kingdoms of this world have become the kingdoms of our Lord and of His Christ, and He shall reign forever and ever!" 16  And the twenty-four elders who sat before God on their thrones fell on their faces and worshiped God, 17  saying: "We give You thanks, O Lord God Almighty, The One who is and who was and who is to come, Because You have taken Your great power and reigned. 18  The nations were angry, and Your wrath has come, And the time of the dead, that they should be judged, And that You should reward Your servants the prophets and the saints, And those who fear Your name, small and great, And should destroy those who destroy the earth.