We read first about the 144,000 in Rev 7, right after the opening of the sixth seal and before the tribulation saints appear in the Throne room of GOD dressed in white robes.
During this passage the 144,000 are being selected and sealed, getting ready for the beginning of their ministry.

Even though the passage appears after the sixth seal is broken, that doesn’t mean they get sealed after the opening of the sixth seal because the book is not written in a strict chronological way. What we know for sure is that the tribulation saints appear in heaven some time after the opening of the sixth seal because they were still waiting after the opening of the fifth seal. (Rev 6:9-11)
In Rev 9:4, after the fifth trumpet, the 144,000 are already sealed. It is not clear if those who have the seal of God on their foreheads are only the 144,000, there could also be some messianic Jews or even some remnants from the church who still need to repent. But what is very clear is that after the sixth trumpet no one else repents. The church is completely gone.
OK, if there is no more repenting of the GENTILES after the sixth trumpet and the tribulation saints appear in heaven after the sixth seal is broken, doesn’t this mean that the trumpets and the seals are somewhat parallel events, since the church is composed mostly by GENTILES?
Yes, the trumpets and the seals are relatively parallel events. We will see this deeply on a future page called the 7 Trumpets and the 7 Seals.
After the church is gone, the only people alive on earth are the tribes of Israel and the unbelievers in YESHUA. The ministry of the Two Witnesses has ended, the first 42 months of the tribulation are over and the Antichrist is about to be revealed as the Abomination of desolation.
The ministry of the 144,000 is about to start.
This moment in time during the tribulation has to be justified. In 2 Thess 2: 1-8, ¨1 Now, brethren, concerning the coming of our Lord Jesus Christ and our gathering together to Him,… 3 Let no one deceive you by any means; for that Day will not come unless the falling away comes first, and the man of sin is revealed, the son of perdition,… 7 For the mystery of lawlessness is already at work; only He who now restrains will do so until He is taken out of the way 8 And then the lawless one will be revealed…”NKJV. To correctly interpret this paragraph we must remember the 24 Elders and the tribulation Saints. The coming of our LORD refers to the rapture, but the gathering together can only occur once the tribulation Saints appear in heaven. It can not be a gathering with an incomplete Church. Now, because the Holy Spirit is within every member of the Church. The restrainer in this paragraph is the Holy Spirit and the church has to leave earth for the antichrist to be revealed.
That’s right, we are at the middle of the tribulation period and it will be proven again from the perspective of the 144,000. In Rev 12:7,9,12-17, “7 And war broke out in heaven: Michael and his angels fought with the dragon; and the dragon and his angels fought,… 9 So the great dragon was cast out, that serpent of old, called the Devil and Satan, who deceives the whole world; he was cast to the earth, and his angels were cast out with him… 12 Therefore rejoice, O heavens, and you who dwell in them! 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. 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, 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.” NKJV. When John sees the beginning of the tribulation (first seal is open), satan is not there so this war started before that and ends at the middle of the tribulation. Satan has been cast down to earth with his angels. This also relates to the sixth seal Rev 6:12-13, “12 I looked when He opened the sixth seal, and behold, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became like blood. 13 And the stars of heaven fell to the earth, as a fig tree drops its late figs when it is shaken by a mighty wind.” NKJV. When satan and his minions fall they will fall as meteors over the earth and over the sea, and their fall will cause tsunamis all over the place. One of these tsunamis will go towards Israel but a big earthquake will split open the earth and deviate the waters. And Israel will be protected in the wilderness for 3 and a half years. And the dragon (satan) will make war against the 144,000. This is the beginning of their ministry, they will defend Israel against the attacks of the devil for 3.5 years.
The next input about the 144,000 occurs in Rev 14:1-5, “1 Then I looked, and behold, a Lamb standing on Mount Zion, and with Him one hundred and forty-four thousand, having His Father’s name written on their foreheads. 2 And I heard a voice from heaven, like the voice of many waters, and like the voice of loud thunder. And I heard the sound of harpists playing their harps. 3 They sang as it were a new song before the throne, before the four living creatures, and the elders; and no one could learn that song except the hundred and forty-four thousand who were redeemed from the earth. 4 These are the ones who were not defiled with women, for they are virgins. These are the ones who follow the Lamb wherever He goes. These were redeemed from among men, being firstfruits to God and to the Lamb. 5 And in their mouth was found no deceit, for they are without fault before the throne of God.” NKJV.
There is a lot of vital information about the 144,000 so let’s start for the most obvious one, they are messianic Jews But the most revealing one: They are firstfruits. As we analyzed for the 24 Elders, in order to be a firstfruit you need an incorruptible body, so the 144,000 will have incorruptible bodies during their ministry. Because they have not being defiled by women it is very probable that they were of very young age when sealed, even infants because of their purity and innocence. I had a vision about this called mirror, mirror on the wall and from that we can imply that all of them will look like 25 year old males at the peak of their lives.
Other important fact is that just like JESUS, the firstfruits have to be offered to GOD as in John 20:16,17 “16 Jesus saith unto her, Mary. She turned herself, and saith unto him, Rabboni; which is to say, Master. 17 Jesus saith unto her, Touch me not; for I am not yet ascended to my Father: but go to my brethren, and say unto them, I ascend unto my Father, and your Father; and to my God, and your God.” KJV.
They will get their glorified bodies, be raptured unto Heaven, be presented unto GOD and to the LAMB, sing the new song that only they can learn and come back to earth to perform their ministry.
But their most amazing quality will be that they can understand GOD ALMIGHTY and the LAMB like no one else can. GOD knows what they will be capable of doing, and they will do it for the last 3.5 years known as the great tribulation.
Let’s remember Rev 6:16, after the opening of the sixth seal, “16 and said to the mountains and rocks, “Fall on us and hide us from the face of Him who sits on the throne and from the wrath of the Lamb! 17 For the great day of His wrath has come, and who is able to stand?”” NKJV. So it is clear JESUS could return after the sixth seal is opened, but because HE is the one opening them, HE has to return after the opening of the 7th seal. However, HE does not have to wait for the sounding of the 7th trumpet.
They follow the lamb wherever HE goes so this part of their ministry will follow a period of time not clearly defined where they alone protect the wheat harvest.
Now with this more detailed description of the 144,000 we see that they fit in the description of the church of Thyatyra. Rev 2:20-25, “20 Nevertheless I have a few things against you, because you allow that woman Jezebel, who calls herself a prophetess, to teach and seduce My servants to commit sexual immorality and eat things sacrificed to idols. 21 And I gave her time to repent of her sexual immorality, and she did not repent. 22 Indeed I will cast her into a sickbed, and those who commit adultery with her into great tribulation, unless they repent of their deeds. 23 I will kill her children with death, and all the churches shall know that I am He who searches the minds and hearts. And I will give to each one of you according to your works. 24 Now to you I say, and to the rest in Thyatira, as many as do not have this doctrine, who have not known the depths of Satan, as they say, I will put on you no other burden. 25 But hold fast what you have till I come.” NKJV. The church of Thyatira is going through deep sexual immorality but JESUS calls on those of this church who are not under that condition, those who are sexually pure, to wait for HIM in purity until HE comes. Those are the 144,000.