What's in the Bible? The Seventh Seal: Wickedness, Destruction & Protection of the Righteous

John gives us extensive description of the events pertaining to the seventh seal.

"And when he had opened the seventh seal, there was silence in heaven about the space of half an hour. And I saw the seven angels which stood before God; and to them were given seven trumpets. And another angel came and stood at the altar, having a golden censer; and there was given unto him much incense, that he should offer it with the prayers of all saints upon the golden altar which was before the throne. And the smoke of the incense, which came with the prayers of the saints, ascended up before God out of the angel’s hand. And the angel took the censer, and filled it with fire of the altar, and cast it into the earth: and there were voices, and thunderings, and lightnings, and an earthquake." (Revelation 8:1-5)
 

Casting incense and coals onto the altar together was something that was done twice daily in the Holy of Holies or the "most holy place" in the temple. A special burning of incense was also done on the day of Atonement, and it was only done by a priest; no one else was allowed to be in the holy place during this activity. The abundance of burning incense created a cloud that separated God from the priest in the holy place that "he die not". (see Leviticus 16:12-13) At the conclusion of the burning of incense, the priest pronounced the following blessing upon the people:

"The Lord bless thee, and keep thee: The Lord make his face shine upon thee, and be gracious unto thee:The Lord lift up his countenance upon thee, and give thee peace." (Numbers 6:24-26)

I believe John has used this imagery for a handful of reasons. First, he is showing the contrast between the holiness of God and His saints and what the world has become in the last days. Secondly, he shows us that the Lord will hear the prayers of the saints pleading for relief from persecution and from life in an increasingly wicked world. The combination of the incense and the prayers of the saints symbolizes the Lord protecting and preserving His people during the destruction of the last days, that "they die not" - a sort of quickening to enable believers to bear the work of destruction prior to His coming. (see Doctrine & Covenants 67:11) I find it instructive that John has metaphorically placed the prayers of saints as the coals from the altar. Who among us has not felt the Spirit of God cause our hearts to burn within us while we prayed? (see Luke 24:32, Revelation 4:5, 3 Nephi 11:2-3) The fire being cast into the earth symbolizes the cleansing of the earth.    Implicit here is the priest's blessing upon the Lord's people through all of this: "The Lord bless thee and keep thee... be gracious unto thee... and give thee peace." Note that the protection to which John refers is from the cleansing work of the Lord and not necessarily from the acts of the wicked. Other protections afforded to the righteous will be explored later.

John tells us the intense destruction associated with the seventh seal would go on for five months:

"And there came out of the smoke locusts upon the earth: and unto them was given power, as the scorpions of the earth have power. And it was commanded them that they should not hurt the grass of the earth, neither any green thing, neither any tree; but only those men which have not the seal of God in their foreheads.  And to them it was given that they should not kill them, but that they should be tormented five months: and their torment was as the torment of a scorpion, when he striketh a man.  And in those days shall men seek death, and shall not find it; and shall desire to die, and death shall flee from them." (Revelation 9:3-6)

He tells us God will allow the destroying angels to destroy the "third part of men" because of their ungodliness and great telestial wickedness:

"And the four angels were loosed, which were prepared for an hour, and a day, and a month, and a year, for to slay the third part of men. And the number of the army of the horsemen were two hundred thousand thousand: and I heard the number of them.  And thus I saw the horses in the vision, and them that sat on them, having breastplates of fire, and of jacinth, and brimstone: and the heads of the horses were as the heads of lions; and out of their mouths issued fire and smoke and brimstone. By these three was the third part of men killed, by the fire, and by the smoke, and by the brimstone, which issued out of their mouths.  For their power is in their mouth, and in their tails: for their tails were like unto serpents, and had heads, and with them they do hurt. And the rest of the men which were not killed by these plagues yet repented not of the works of their hands, that they should not worship devils, and idols of gold, and silver, and brass, and stone, and of wood: which neither can see, nor hear, nor walk:  Neither repented they of their murders, nor of their sorceries, nor of their fornication, nor of their thefts." (Revelation 9:15-21)

A great battle of all nations at armageddon will mark the end of the five months' destruction

https://www.lds.org/scriptures/nt/rev/16?lang=eng