At the middle of the 7-year Tribulation, the Antichrist sits in the (3rd) Temple of God of Israel, showing himself and the world that he is “god” - yes, there will be a 3rd Temple.
Matthew 24:15-23 King James Version
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:
17 Let him which is on the housetop not come down to take any thing out of his house:
18 Neither let him which is in the field return back to take his clothes.
19 And woe unto them that are with child, and to them that give suck in those days!
20 But pray ye that your flight be not in the winter, neither on the sabbath day:
21 For then shall be >>>>Great Tribulation<<<<, such as was not since the beginning of the world to this time, no, nor ever shall be.
22 And except those days should be shortened, there should no flesh be saved: but for the elect’s sake those days shall be shortened.
23 Then if any man shall say unto you, Lo, here is Christ, or there; believe it not.
The Day of the Lord
2 Thessalonians 2:3-4 King James Version
3 Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition;
4 Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.
Notice there are no references to a seven year time period in Revelation, you'll find time, times and half a time, three and a half days (years actually) and 42 months, all three and a half years. So where is the other half?
Two witnesses, every matter must be established by at least two witnesses.
John 8:17 In your own Law it is written that the testimony of two witnesses is true. 18 I am one who testifies for myself; my other witness is the Father, who sent me.”
2 Corinthians 13:1 This will be my third visit to you. “Every matter must be established by the testimony of two or three witnesses.”
Revelation 1:1 The Revelation of Yeshua HaMashiach, which God gave Him to show His servants—things which must shortly take place. And He sent and signified it by His angel to His servant John, 2 who bore witness to the word of God, and to the testimony of Yeshua HaMashiach, to all things that he saw.
Revelation 1:19 Write the things which you have seen, and the things which are, and the things which will take place after this. (Yeshua)
Revelation 4:4 After these things I looked, and behold, a door standing open in heaven. And the first voice which I heard was like a trumpet speaking with me, saying, “Come up here, and I will show you things which must take place after this.”
Notice: things which must shortly take place, Write the things which you have seen, and the things which are, and the things which will take place after this, “Come up here, and I will show you things which must take place after this.”
Yohannan was on the isle of Patmos, that is your reference point.
Search the book of Revelation and you'll not find a seven year time period. You'll find 1260 days, 30 (Hebrew months) x 42 = 3.5 years
Three and a half days, actually it's Yud Mem Yud Mem, modern Hebrew it's 'year'. 42 months and mirroring Daniel a time, times and half a time, all three and a half years, that is the duration of the great tribulation.