A parallel reference is 1 Corinthians 15:51-53 1 Corinthians 15:51-53  Behold, I show you a mystery; We shall not all sleep, but we shall all be changed,
 In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
 For this corruptible must put on incorruption, and this mortal must put on immortality.
American King James Version×, in which Paul plainly tells us that God will resurrect deceased believers to spirit at "the last trumpet." This is the same "trumpet of God" mentioned in 1 Thessalonians 4:16 1 Thessalonians 4:16For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first:
American King James Version×. Paul further states in 1 Corinthians 15:51 1 Corinthians 15:51Behold, I show you a mystery; We shall not all sleep, but we shall all be changed,
American King James Version×that God will also change believers who are still living at the time into spirit. So the return of Jesus Christ and the resurrection of the saints occur in the same time period.
What is the significance of the trumpet of which Paul wrote? The book of Revelation tells of seven trumpets sounded by seven angelic beings at the end of the age (the first six coming in chapters 8-9). The drama builds through each event announced by a trumpet blast until the seventh and final angel sounds in Revelation 11. His announcement is the finale, the last and greatest event: The return of Jesus Christ to inaugurate the Kingdom of God on earth.
"Then the seventh angel blew his trumpet, and there were loud voices in heaven, saying, 'The kingdom of the world has become the kingdom of our Lord and of his Christ, and he shall reign forever and ever!'" (Revelation 11:15 Revelation 11:15And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.
American King James Version×, English Standard Version).
This trumpet announces the coming of divine wrath and the time of rewarding God's servants (Revelation 11:18 Revelation 11:18And the nations were angry, and your wrath is come, and the time of the dead, that they should be judged, and that you should give reward to your servants the prophets, and to the saints, and them that fear your name, small and great; and should destroy them which destroy the earth.
American King James Version×). And combined with the other verses, it's clear that Jesus descends at the blowing of this seventh trumpet—and that this is when the saints are caught up to Him.
When does this occur in the timeline of end-time events? In a prophecy Jesus gave, He referred to a desecration in Jerusalem—the abomination of desolation—to come before the Great Tribulation (Matthew 24:15-22 Matthew 24:15-22  When you therefore shall see the abomination of desolation, spoken of by Daniel the prophet, stand in the holy place, (whoever reads, let him understand:)
 Then let them which be in Judaea flee into the mountains:
 Let him which is on the housetop not come down to take any thing out of his house:
 Neither let him which is in the field return back to take his clothes.
 And woe to them that are with child, and to them that give suck in those days!
 But pray you that your flight be not in the winter, neither on the sabbath day:
 For then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be.
 And except those days should be shortened, there should no flesh be saved: but for the elect's sake those days shall be shortened.
American King James Version×). This event would come 1,290 days before Daniel's resurrection at Christ's return (Daniel 12:11-13 Daniel 12:11-13  And from the time that the daily sacrifice shall be taken away, and the abomination that makes desolate set up, there shall be a thousand two hundred and ninety days.  Blessed is he that waits, and comes to the thousand three hundred and five and thirty days.  But go you your way till the end be: for you shall rest, and stand in your lot at the end of the days.
American King James Version×), just over 3 1⁄2 years.
Jesus continued in Matthew 24:29 Matthew 24:29Immediately after the tribulation of those days shall the sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken:
American King James Version×: "Immediately after the tribulation of those days the sun will be darkened, and the moon will not give its light; the stars will fall from heaven, and the powers of the heavens will be shaken." He said that all nations on earth would see the sign of His coming and would mourn. Then He stated that they would see Him coming with power and glory and that He would send His angels to gather His resurrected followers with a great sound of a trumpet (Matthew 24:30-31 Matthew 24:30-31  And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.  And he shall send his angels with a great sound of a trumpet, and they shall gather together his elect from the four winds, from one end of heaven to the other.
American King James Version×).
Compare this with Revelation 6, where we find a time of terrible final martyrdom (Revelation 6:9-11 Revelation 6:9-11  And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held:
 And they cried with a loud voice, saying, How long, O Lord, holy and true, do you not judge and avenge our blood on them that dwell on the earth?
 And white robes were given to every one of them; and it was said to them, that they should rest yet for a little season, until their fellow servants also and their brothers, that should be killed as they were, should be fulfilled.
American King James Version×). This is followed by the heavenly signs Jesus was referring to and the people of the earth lamenting (Revelation 6:12-17 Revelation 6:12-17  And I beheld when he had opened the sixth seal, and, see, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became as blood;  And the stars of heaven fell to the earth, even as a fig tree casts her untimely figs, when she is shaken of a mighty wind.  And the heaven departed as a scroll when it is rolled together; and every mountain and island were moved out of their places.  And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men, and every slave, and every free man, hid themselves in the dens and in the rocks of the mountains;  And said to the mountains and rocks, Fall on us, and hide us from the face of him that sits on the throne, and from the wrath of the Lamb:  For the great day of his wrath is come; and who shall be able to stand?
American King James Version×). Notice the conclusion of the lament: "For the great day of His wrath has come, and who is able to stand?"
This corresponds to Joel 2:31 Joel 2:31The sun shall be turned into darkness, and the moon into blood, before the great and terrible day of the LORD come.
American King James Version×, where we are told that "the sun shall be turned into darkness, and the moon into blood, before the coming of the great and awesome day of the Lord." That means that, in the book of Revelation, the trumpets blown after the heavenly signs represent the time of the Day of the Lord.
The seventh trumpet comes at the end of this year-long Day of the Lord—at the end of the 3 1⁄2-year period of end-time calamity. The dead in Christ are raised and living believers are changed and made immortal at this point in time. They cannot have been taken up into glory before the tribulation period. Scripture doesn't allow for a rapture of the saints to heaven for an interim of several years!
Protection for the saints
We see that believers aren't taken off the earth during the Great Tribulation. But God will protect believers during this time of severe distress. The most specific reference to the protection that God promises for His people at the end of the age is in Revelation 12.
Revelation 12:14 Revelation 12:14And to the woman were given two wings of a great eagle, that she might fly into the wilderness, into her place, where she is nourished for a time, and times, and half a time, from the face of the serpent.
American King James Version×says, "But the woman [symbolic here of spiritual Israel, the Church of God] 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, from the presence of the serpent." The times here denote years—one (time) plus two (times) plus one half (half a time), equaling 3 1⁄2 years, the period of the Great Tribulation and Day of the Lord. And note that the protection is not in heaven but in the wilderness, or the desert as it's often translated. It's on the earth, not in heaven.
There's more to the story. The context tells us that at least part of God's people will suffer persecution while God protects the rest of the faithful: "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" (Revelation 12:17 Revelation 12:17And the dragon was wroth with the woman, and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ.
American King James Version×). It is possible that the result of this persecution will be martyrdom.
The Bible records many ways by which God protected His people in the past, but does not reveal specifically how, where or when—or even all of the "who"—He will protect in the end. However, we can have confidence that He will reveal what we need to know at the essential time. In the meantime, our focus must be on the spiritual preparation for Christ's return and the establishment of our Father's Kingdom (Matthew 24:38-51 Matthew 24:38-51  For as in the days that were before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noe entered into the ark,
 And knew not until the flood came, and took them all away; so shall also the coming of the Son of man be.
 Then shall two be in the field; the one shall be taken, and the other left.
 Two women shall be grinding at the mill; the one shall be taken, and the other left.
 Watch therefore: for you know not what hour your Lord does come.
 But know this, that if the manager of the house had known in what watch the thief would come, he would have watched, and would not have suffered his house to be broken up.
 Therefore be you also ready: for in such an hour as you think not the Son of man comes.
 Who then is a faithful and wise servant, whom his lord has made ruler over his household, to give them meat in due season?
 Blessed is that servant, whom his lord when he comes shall find so doing.
 Truly I say to you, That he shall make him ruler over all his goods.
 But and if that evil servant shall say in his heart, My lord delays his coming;
 And shall begin to smite his fellow servants, and to eat and drink with the drunken;
 The lord of that servant shall come in a day when he looks not for him, and in an hour that he is not aware of,
 And shall cut him asunder, and appoint him his portion with the hypocrites: there shall be weeping and gnashing of teeth.
American King James Version×).