1 The fifth angel blew his trumpet, and I saw a star that had fallen from heaven to earth. The key to the shaft of the abyss was given to him.
The fifth trumpet initiates the opening of the gates of hell (the abyss, Luke 8:31).
The phrase “I saw a star that had fallen from heaven to earth” most likely refers to an angel from the Lord who has the keys to hell and is given the command to open it. We see this illustrated in Revelation 20:1-3 which says, Then I saw an angel coming down from heaven with the key to the abyss and a great chain in his hand. 2 He seized the dragon, that ancient serpent who is the Devil and Satan, and bound him for 1,000 years. 3 He threw him into the abyss, closed it, and put a seal on it so that he would no longer deceive the nations until the 1,000 years were completed. After that, he must be released for a short time.
2 He opened the shaft of the abyss, and smoke came up out of the shaft like smoke from a great furnace so that the sun and the air were darkened by the smoke from the shaft.
Here the abyss is being described as a furnace which has to be an enormous fire because of the tremendous smoke coming out of it. A parallel in regards of smoke coming out we see that in Revelation 14:11 where it talks about those who received the mark of the beast will be cast into the Lake of Fire and their smoke will ascend up into the presence of the Lord and His angels. It would be safe to say that the abyss is Hades and the demons that come out of Hades are those that are mentioned in Jude 1:6 which says, and He has kept, with eternal chains in darkness for the judgment of the great day, the angels who did not keep their own position but deserted their proper dwelling.
It also describes them in 2 Peter 2:4 which says, 4 For if God didn’t spare the angels who sinned but threw them down into Tartarus and delivered them to be kept in chains of darkness until judgment;
“Tartarus” is defined in Strong’s number “5020 (tartaróō) is a Greek name for the under-world, especially the abode of the damned – hence to cast into hell” (A-S); to send into the subterranean abyss reserved for demons and the dead.
The angels that fell away is described in Genesis 6:1-4 which was after the rebellion of Lucifer and the one-third of the angels that followed him and were thrown out of heaven.
3 Then locusts came out of the smoke on to the earth, and power was given to them like the power that scorpions have on the earth.
The torment that the demons will inflict will resemble a scorpion’s venom.
4 They were told not to harm the grass of the earth, or any green plant, or any tree, but only people who do not have God’s seal on their foreheads.
These demons/locusts have one purpose and one target, those who don’t have the seal of God on their foreheads to torment them.
The phrase “God’s seal” could be a reference to the Holy Spirit as mentioned in Ephesians 1:13 which says, When you heard the message of truth, the gospel of your salvation, and when you believed in Him, you were also sealed with the promised Holy Spirit.
It could be that the sign of having the Holy Spirit will be visible on the forehead.
Another possibility of what the seal could be is seen in Revelation 22:4 which says, They will see His face, and His name will be on their foreheads.
Whatever that seal is, it will be no question to the demons that you belong to Christ and are protected which will make you off-limits to their sting.
5 They were not permitted to kill them but were to torment them for five months; their torment is like the torment caused by a scorpion when it strikes a man.
Here we see God’s mercy that even though He will punish the unbelievers they will not die. The Lord still gives them an opportunity to repent.