If Matt 24:15, Mark 13:14 and Luke 21:20 are speaking of the Roman armies surrounding Jerusalem, and that this is the fulfilment of Dan 9:27b “And on the wing of abominations shall come one who makes desolate, until the decreed end is poured out on the desolator.”, then what is 2 Thes 2:1-4 speaking of, in particular “So he will seat himself in the temple of God, proclaiming himself to be God.”?
Only Luke 21:20 appears to be involving the Roman armies surrounding Jerusalem, thus no connection to Daniel 9:27b nor 2 Thessalonians 2:1-4.
Matthew 24:15 and Mark 13:14 though, these are involving Daniel 9:27b, where that is involving 2 Thessalonians 2:1-4.
If one will notice, the following in Luke 21 makes it clear, or at least to some of us anyway, that Jerusalem is being surrounded twice, not just once.
Luke 21:24 And they shall fall by the edge of the sword, and shall be led away captive into all nations: and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled.
And they shall fall by the edge of the sword, and shall be led away captive into all nations---this is what happened during verse 20. The fact the times of the Gentiles is yet to be fulfilled, and the fact the text tells us Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled, this tells us that Luke 21:20 is not the end of the story involving Jerusalem. In Luke 21:20 that is only meaning up to 70 Ad, thus there is a gap of at least 2000 years in Luke 21 until the coming in Luke 21:27 takes place.
In Matthew 24:15 and Mark 13:14 there is not a gap of 2000 years after those are fulfilled, that the coming in those chapters take place. Let's focus on the Matthew 24 account to try and keep it simple since we already know the Mark 13 account is it's parallel.
Matthew 24:15 When ye therefore shall see the abomination of desolation, spoken of by Daniel the prophet, stand in the holy place, (whoso readeth, let him understand: )
In Luke 21 Matthew 24:15 is not meaning during Luke 21:20, this is meaning during this recorded in Luke 21:24---and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled. Matthew 24:15 is meaning in the end of this age towards the end of the 2000 year gap that began with Luke 21:20. Personally, I take this gap to be involving the gap concerning the 70 weeks. Either that gap is between the 69th and 70th week or it's in the middle of the 70th week. Regardless where it might be, there is clearly a gap there, yet many deny a gap is involved even though it is plainly obvious there has to be.
Matthew 24:29 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, and the powers of the heavens shall be shaken:
This is why Luke 21:20 can't be meant in Matthew 24:15-22. The tribulation of those days are undeniably meaning Matthew 24:15-26 and that immediately after Luke 21:20 was fulfilled, what is recorded in Matthew 24:29 did not follow any of that. A gap followed the fulfillment of Luke 21:20 and that we are still apparently experiencing this gap as we speak since Matthew 24:15-26 has to be fulfilled before the coming recorded in Matthew 24:30 can take place.
Since this post is already getting rather lengthy, Matthew 24:15-26 involves 2 Thessalonians 2:1-4. 2 Thessalonians 2:1-4 is involving Revelation 13 and the 42 month reign of the beast.
We can see the connection with all 3 like this for one.
Matthew 24:24 For there shall arise false Christs, and false prophets,
and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect.
2 Thessalonians 2:9 Even him, whose coming is after
the working of Satan with all power and signs and lying wonders,
Revelation 13:11 And I beheld another beast coming up out of the earth; and he had two horns like a lamb, and he spake as a dragon.
12 And he exerciseth all the power of the first beast before him, and causeth the earth and them which dwell therein to worship the first beast, whose deadly wound was healed.
13
And he doeth great wonders, so that he maketh fire come down from heaven on the earth in the sight of men,
14 And deceiveth them that dwell on the earth by the means of those miracles which he had power to do in the sight of the beast; saying to them that dwell on the earth, that they should make an image to the beast, which had the wound by a sword, and did live.
What I have underlined couldn't possibly be involving Luke 21:20, yet it is involving Matthew 24:15-22, and still there are many that would have us believe that Matthew 24:15-22 parallels Luke 21:20.