Do you understand that Matthew and Luke were writing to different audiences? Matthew was writing to Jews and Luke was writing to Gentiles. That is what accounts for the differences in Matthew 24:15 and Luke 21:20. Matthew's audience was familiar with the prophecies in Daniel which is why it says "let the reader understand". Luke's audience of Gentiles would have known nothing about Daniel's prophecies, so it would make no sense for Luke to tell them to consider the prophecy in Daniel about the abomination of desolation and then to say "let the reader understand".
If you insist on continuing to claim that Matthew 24:15-22 and Luke 21:20-24a are not parallel accounts, then you need to show exactly when you think Jesus said what He did in Matthew 24:15-22 in relation to when He said what He did in Luke 21:20-24. Can you please do that? Please combine Matthew 24 and Luke 21 together to show your understanding of when He said what. At least as it relates to those two passages.
So, if you think He said what is recorded in Luke 21:20-24 after what He said in Matthew 24:15-22, then please show when you think He said what up to that point. Or if you think He said what is recorded in Matthew 24:15-22 after what He said in Luke 21:20-24a then show it up to that point. This is the only way that I can take you seriously is if you can give some kind of evidence that makes some kind of sense as to how those two passages could possibly not be parallel.
Some of this below is not for your benefit, but is for the benefit of others, meaning anyone who might think what is recorded in Matthew 24 and Luke 21 are not involving a same particular day Jesus was teaching in the temple.
In Mattthew the following appears to be when He initially entered the temple that day, the same day He is seen leaving it in Matthew 24.
Matthew 21:23 And when he was come into the temple, the chief priests and the elders of the people came unto him as he was teaching, and said, By what authority doest thou these things? and who gave thee this authority?
24 And Jesus answered and said unto them, I also will ask you one thing, which if ye tell me, I in like wise will tell you by what authority I do these things.
25 The baptism of John, whence was it? from heaven, or of men? And they reasoned with themselves, saying, If we shall say, From heaven; he will say unto us, Why did ye not then believe him?
26 But if we shall say, Of men; we fear the people; for all hold John as a prophet.
27 And they answered Jesus, and said, We cannot tell. And he said unto them, Neither tell I you by what authority I do these things.
Now let's go to Luke and also try and determine when Jesus ininitially enters the temple He is seen in in Luke 21.
Luke 20:1 And it came to pass, that on one of those days, as he taught the people in the temple, and preached the gospel, the chief priests and the scribes came upon him with the elders,
2 And spake unto him, saying, Tell us, by what authority doest thou these things? or who is he that gave thee this authority?
3 And he answered and said unto them, I will also ask you one thing; and answer me:
4 The baptism of John, was it from heaven, or of men?
5 And they reasoned with themselves, saying, If we shall say, From heaven; he will say, Why then believed ye him not?
6 But and if we say, Of men; all the people will stone us: for they be persuaded that John was a prophet.
7 And they answered, that they could not tell whence it was.
8 And Jesus said unto them, Neither tell I you by what authority I do these things.
If this doesn't undeniably prove that both Matthew 24 and Luke 21 are involving a same particular day Jesus was in the temple, then I give up. IOW, Matthew 24 isn't involving a particular day that Jesus was teaching in the temple, and that Luke 21 is involving another particular day, thus the same day is not meant. Clearly that is wrong. Both accounts are involving this same particular day in question. But even so, we still don't know what it looked like at the time when Jesus was predicting what He did. Meaning, did He say this first, then later say this, thus, though they appear to be involving the same events, they really aren't.
For example.
Luke 21:20 And when ye shall see Jerusalem compassed with armies, then know that the desolation thereof is nigh.
21 Then let them which are in Judaea flee to the mountains; and let them which are in the midst of it depart out; and let not them that are in the countries enter thereinto.
This is what is recorded in Luke 21.
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: )
16 Then let them which be in Judaea flee into the mountains:
How can these be involving the same events if one account records one is to flee to the mountains when ye shall see Jerusalem compassed with armies, and the other account records one is to flee to the mountains when ye therefore shall see the abomination of desolation, spoken of by Daniel the prophet, stand in the holy place?
In the Luke 21:20 account, the armies are surrounding Jerusalem, not inside of Jerusalem overthrowing it yet. In the Matthew 24:15 account, it is when one sees the abomination of desolation, spoken of by Daniel the prophet, stand in the holy place(temple), one is to then flee. How can that mean this----when ye shall see Jerusalem compassed with armies.? The fact they would be outside of Jerusalem, and that the holy place would be inside of Jerusalem, how could these be describing the same events?
Is one going to argue that the holy place is not meaning a temple, but is meaning outside of Jerusalem, that the armies surrounding it, this equals standing in the holy place? As if that makes some kind of sense, keeping in mind that Luke 21:20 is to be taken literally when it indicates Jerusalem is being surrounded with armies. And if Matthew 24:15 is recording this same event, then so must this part be taken literal as well---the abomination of desolation---stand in the holy place. Which then means the armies have to be inside Jerusalem at the time, then one is to flee to the mountains. But how could they be inside of Jerusalem when one is to flee to the mountains, if Luke 21:20 records they are to flee before the armies ever enter Jerusalem in order to try and overthrow it.
And what about the temple recorded in 2 Thessalonians 2:4, which plays a major role in the end of this age prior to His 2nd coming? One is to believe, though Matthew 24 records His 2nd coming(verse 31), Jesus is just going to skip over anything involving 2 Thessalanians 2:4, and instead go from 2000 years earlier to that of His coming 2000 years later without Him predicting anything that might pertain to the end of this age, such as what is recorded in 2 Thessalonians 2? Or what is recorded in Revelation 13 involving the 42 month reign of the beast?
