There is no scripture which says point blank that the Church is the temple of God. But if as we know every member of the Church is the temple of God then the church collectively can be looked at as the temple of God. The Antichrist will deceive the whole world meaning his influence will be worldwide. Putting him in a actual temple in Jerusalem is not really going to do it. God has already left the temple desolate and even if a new one is rebuilt it cannot be termed 'The temple of God' because God will not be dwelling there.
When you put the event in the future you will have this problem.
Luk 21:20 And when ye shall see Jerusalem compassed with armies, then know that the desolation thereof is nigh.
Luk 21:21 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.
Luk 21:22 For these be the days of vengeance, that all things which are written may be fulfilled.
But if you look at the text simply and compare Luke's account with Matthews the answer is simple. Matthew says..
Mat 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
The abomination comes from these armies being in the holy place where they ought not to be. If you know how Jerusalem was, there was a certain area around the city which was holy. These armies would therefore be compassed in this holy place around the city where they should not be. These are the armies which bring the destruction upon the city. If you are looking for an Antichrist to fulfill this prophecy you are looking the wrong place. Luke 21:22 tells us that this will happen to fulfill scripture. Which prophecy does these armies fulfill other than the 70 week prophecy?
If you don't guard yourself you will be deceived. Think about it really. Why would Satan seek the deceive those who are already lost? What does he gain by that. The devil's attack is on the church and not those outside the church. He seeks to have us who are in Christ to leave and join his side, this the Antichrist is not going to be someone who Christians already don't like. The devil has never ever worked that way. Lets look at the text which speaks about the Antichrist again.
2Th 2:3 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;
2Th 2:4 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.
All I am going to ask is how can you fall away if you were never once there. This falling away is a falling away of Christians who got deceived. People who are lost cannot fall away for they have already fallen. Only saved people can fall away.
Heb 6:4 For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,
Heb 6:5 And have tasted the good word of God, and the powers of the world to come,
Heb 6:6 If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.