In these sermons the Day of the Lord is the time when God's wrath is poured out on the earth. A "day" in Scripture can mean a period, as in the six days of creation; this one is the last forty-five days of the sermons' timeline. It begins when the seventh trumpet sounds and seven angels bring out the seven plagues in golden vials.
On that timeline it comes after the rapture, after the great tribulation (42 months, or 1,260 days), and after thirty more days, the "one hour" in which ten kings rule with the Antichrist. It ends on day 1,335. Part 1 counts the thirty and forty-five days together as seventy-five. The physical detail below is the sermons' own picture, often offered with "may" and "perhaps".
Part 1 — Signs, a Shaken Earth and the First Vials
Immediately 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…
— Matthew 24:29
Part 1 places these signs right after the great tribulation; Part 3, at the start of the forty-five days. Joel 2:31 and the sixth seal (Revelation 6:12) describe the same black sun and blood-red moon; the seal's other events come at the very end. Part 1 reads the falling stars as meteors, which a large, fast body from space passing close to the earth could bring down. Coming between sun and earth, it could also darken the sun and leave the moon dimly red, perhaps for much of the forty-five days. Its passing would jolt the earth in its orbit (Isaiah 13:13; 24:19–20), so the sky seems to shake, and draw the earth nearer the sun, to fierce heat and melting elements (2 Peter 3:10).
Believers who walk in the Lord's way and receive the message of the seven thunders are taken in the rapture. Those who believed and were baptised but did not prepare are left behind, hear the two witnesses and then the 144,000, refuse the mark and die as martyrs. Only the 144,000 and the woman, Israel, are kept safe; the wicked die under God's wrath until, as Isaiah 24:6 says, few men are left.
The first six vials fall in this setting: sores on those with the mark; sea, rivers and springs turned to blood; the sun scorching men; darkness over the beast's kingdom, read as the loss of God's word, since those who taught it are dead or perhaps in hiding; and the Euphrates dried up.
Read more in Part 1: A Shaken Earth and the Vials of Wrath.
Part 2 — The Sixth Vial and Armageddon
The Euphrates dries up "that the way of the kings of the east might be prepared", and unclean spirits gather the kings of the whole world to Armageddon (Revelation 16:12–16). Part 2 suggests who these kings are. The Antichrist rules many nations because they signed the covenant, and bound by it they keep still; but China and India may stand outside it and fight each other, which would be the sixth trumpet's war that kills a third of mankind. The victor and his vast army, unaware that the Lord already reigns, may then cross the dry Euphrates and march on Jerusalem, where the Antichrist sits in God's temple.
At Armageddon the Lord treads this army like grapes in a winepress, the blood rising to the horses' bridles (Isaiah 63:1–6; Revelation 14:17–20). The sermon cannot say how.
Next come the ten kings, ten European nations joined like the European Union or NATO, who in their thirty days shut down the 666 system. Still thinking the kingdom theirs, they gather to make war with the Lamb, who overcomes them (Revelation 17:14). Around the sixth plague the church receives the Lamb's "marriage supper": God's word and plans for the kingdom ahead. Heaven opens on a rider on a white horse, the Word of God, followed by his wife, the church, in white linen. His word, the sword from his mouth, strikes the ten kings down. The beast and the false prophet are cast alive into the lake of fire, the first to go there.
Read more in Part 2: The Sixth Vial and the Battle of Armageddon.
Part 3 — The Seventh Vial and the Lord's Descent
The seventh vial brings the greatest earthquake since men were upon the earth (Revelation 16:17–21): islands flee, mountains are not found, and hailstones of about forty kilograms fall on men.
Part 3 pictures how this may come about. Shaken nearer the sun, the earth scorches on one side while vapour freezes and falls as hail on the other. The scorched seas, about seventy-one per cent of the earth, dry away as vapour, and the moon's pull, which now raises the tides, falls on the land itself: the sea floor rises, mountains sink and the great plates shift until the earth is level. Part 3 reads Revelation 21:1, "there was no more sea", as this same earth made new.
Other Scriptures describe the same day: kings and the mighty hide in caves and ask the mountains to fall on them (Revelation 6:12–17), while mountains melt like wax and the ground itself rises and falls in waves (Micah 1; Amos 8–9).
Very few survive: the woman, Israel, who fled for 1,260 days, and a few others who barely escape. Those who reach day 1,335 are called blessed. The earth, cleansed of the wicked, has settled, though not fully. Then the Lord comes down.
And his feet shall stand in that day upon the mount of Olives…
— Zechariah 14:4
He enters Jerusalem, sits on his throne and rules the world. Part 3 stresses that, though the Lord took the kingdom when the forty-five days began, he had not yet come down; Part 2 describes his victory at Armageddon as heaven opened. The plagues have cleared the earth, not of rubbish but of the people he does not want; he keeps the few good alive to rule over, though not all of them please him.
Read more in Part 3: The Seventh Vial and the Great Earthquake.
Takeaway
Believers who walk in the Lord's way now will be ready to meet him; belief and baptism without that preparation leave a person behind. We are to take these events seriously, hold firm in his word and truth, and be among those who come with him, not those who remain on the earth. A red moon seen today means nothing; the sign to watch for comes after the great tribulation ends.