Not at all. Let me clarify what I believe His main theme is. His main theme is not just the the gathering of believers, but also the other part of what occurs at Christ's coming, which is His vengeance on unbelievers. He does allude to that in verses 8 and 12.
I see no reason to think that he needed to refer to it specifically after verse 2 (the day of the Lord = the second coming and all it entails, including the rapture). The focus of the passage is much more on what happens to unbelievers when Christ comes (see verses 8-12) than what happens to believers. I imagine that is because he already wrote to them in detail about what happens to believers on that day in 1 Thess 4:13-18 and 2 Thess 1:10.
But, we don't agree that the wrath that Paul says comes suddenly on the day of the Lord is the same wrath that Peter says will come on the day of the Lord in 2 Peter 3:10-13. It's very obvious to me that they are speaking of the same thing because, for one thing, they are both speaking of events in relation to God's wrath that comes at the second coming of Christ. Also, Paul said that "they will not escape" and with fire coming down on the entire earth, as Peter mentioned, it makes sense that they would not escape that.
We've already been over this, but I'll say again that what is described in Rev 6:12-17 is all symbolic language. I pointed out before that it can't be speaking of literal stars falling to the earth because that would completely annihilate the earth. It's all symbolic language to describe the totality of the destruction that will occur when Christ returns (which lines up with 2 Peter 3:10-13).
As to whether it describes God's wrath or not...why do you need anyone to help you determine that? It obviously is.
Rev 6:15 Then the kings of the earth, the princes, the generals, the rich, the mighty, and everyone else, both slave and free, hid in caves and among the rocks of the mountains. 16 They called to the mountains and the 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 their wrath has come, and who can withstand it?”
I am honestly completely baffled as to how you would wonder whether this is describing the wrath of God or not. Isn't it obvious?
His real main them is made very clear by his choice of words:
"By"
"As touching"
"In regard to"
"Concerning"
"about"
"in Connection with"
the coming of the Lord Jesus Christ and our gathering to meet Him.
This is not just a disagreement over words: it is understanding the English language: Paul is telling us THIS SUBJECT is what I am going to be writing about.
Take careful note: He COULD have written:
"Concerning the Day of the Lord" but he didn't.
"Concerning the revealing of the man of sin" but he didn't.
I can guess - and it is only a guess - the reason he stated it like this is because the timing of the rapture in relation to the Day of the Lord is WHY THEY WROTE TO HIM asking him. It seems some or all of them had begun to believe that the DAY had come and they were IN IT, but were not raptured or caught up.
(the day of the Lord = the second coming and all it entails, including the rapture).
Yet, not one hint of anything good about the DAY in all of the OT mentions of this Day of the Lord. Even Paul, in 1 Thes. 5 compares the Day of the Lord to "sudden destruction" and to His wrath.
Because God will set no appointments for us with His wrath, I believe the rapture will come first, and then the Day of Wrath will begin, as if the rapture will be the trigger for the Day. The DAY is a dark day of destruction. WHY do I believe this?
Amos 5:18
Woe unto you that desire the day of the Lord! to what end is it for you? the day of the Lord is darkness, and not light.
If the Rapture and Day of the Lord were speaking of the same thing; this verse makes no sense: We all eagerly wait for the rapture, so if they are the same, this verse is wrong.
Which one of these verses gives us ANY hint of a rapture / gathering as part of the DAY?
Isaiah 2:12
For the day of the Lord of hosts shall be upon every one that is proud and lofty, and upon every one that is lifted up; and he shall be brought low: [The Day of the Lord is for the proud.]
Isaiah 13:6
Howl ye; for the day of the Lord is at hand; it shall come as a destruction from the Almighty. [The day of the Lord is destruction.]
Isaiah 13:9
Behold, the day of the Lord cometh, cruel both with wrath and fierce anger, to lay the land desolate: and he shall destroy the sinners thereof out of it. [the Day of the Lord is cruel and comes with fierce anger.]
Isaiah 34:8
For it is the day of the Lord's vengeance, and the year of recompences for the controversy of Zion.
Jeremiah 46:10
For this is the day of the Lord God of hosts, a day of vengeance, that he may avenge him of his adversaries: and the sword shall devour, and it shall be satiate and made drunk with their blood: for the Lord God of hosts hath a sacrifice in the north country by the river Euphrates.
[The day of the Lord is about vengeance.]
Lamentations 2:22
Thou hast called as in a solemn day my terrors round about, so that in the day of the Lord's anger none escaped nor remained: those that I have swaddled and brought up hath mine enemy consumed.
[The day of the Lord is a day of anger.]
Ezekiel 13:5
Ye have not gone up into the gaps, neither made up the hedge for the house of Israel to stand in the battle in the day of the Lord. [the Day of the Lord will include BATTLE.]
Ezekiel 30:3
For the day is near, even the day of the Lord is near, a cloudy day; it shall be the time of the heathen. [The Day of the Lord is for the heathen.]
Joel 1:15
Alas for the day! for the day of the Lord is at hand, and as a destruction from the Almighty shall it come. [The Day of the Lord is about destruction. "Alas" for that day.]
Joel 2:11
And the Lord shall utter his voice before his army: for his camp is very great: for he is strong that executeth his word: for the day of the Lord is great and very terrible; and who can abide it? [The Day of the Lord is very terrible and who can abide it?]
Amos 5:20
Shall not the day of the Lord be darkness, and not light? even very dark, and no brightness in it? [Does this sound like the rapture?]
Obadiah 1:15
For the day of the Lord is near upon all the heathen: as thou hast done, it shall be done unto thee: thy reward shall return upon thine own head. [The Day of the Lord is for the heathen, not the saved.]
Zephaniah 1:7
Hold thy peace at the presence of the Lord God: for the day of the Lord is at hand: for the Lord hath prepared a sacrifice, he hath bid his guests. [The Day of the Lord will include a great sacrifice of the guests invited: THEY are the sacrifice. This tells me that Armageddon will be a part of the Day of the Lord.]
Zephaniah 1:8
And it shall come to pass in the day of the Lord's sacrifice, that I will punish the princes, and the king's children, and all such as are clothed with strange apparel [The Day of the Lord is about punishment. ]
Zephaniah 1:14
The great day of the Lord is near, it is near, and hasteth greatly, even the voice of the day of the Lord: the mighty man shall cry there bitterly. [The Day of the Lord is when people cry bitterly.]
Zephaniah 1:18
Neither their silver nor their gold shall be able to deliver them in the day of the Lord's wrath; but the whole land shall be devoured by the fire of his jealousy: for he shall make even a speedy riddance of all them that dwell in the land. [The land is devoured by fire during the Day of the Lord.]
Zephaniah 2:2
Before the decree bring forth, before the day pass as the chaff, before the fierce anger of the Lord come upon you, before the day of the Lord's anger come upon you. [The Lord's anger is FIERCE during the Day.]
Zephaniah 2:3
Seek ye the Lord, all ye meek of the earth, which have wrought his judgment; seek righteousness, seek meekness: it may be ye shall be hid in the day of the Lord's anger. [There will be an escape and a hiding place during the Day.]
Zechariah 14:1
Behold, the day of the Lord cometh, and thy spoil shall be divided in the midst of thee. [Spoil speaks of battle and being overcome.]
Malachi 4:5
Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the Lord:
[The Day of the Lord will be a dreadful day.]
Again, I ask: in which of these verses can you find a hint of a rapture or gathering to Him?