Better to read what Irenaeus himself actually said:
Irenaeus:
4. "But he indicates the number of the name now, that when this man comes we may avoid him, being aware who he is: the name, however, is suppressed, because it is not worthy of being proclaimed by the Holy Spirit. For if it had been declared by Him, he (Antichrist) might perhaps continue for a long period. But now as "he was, and is not, and shall ascend out of the abyss, and goes into perdition,"(1) as one who has no existence; so neither has his name been declared, for the name of that which does not exist is not proclaimed. But when this Antichrist shall have devastated all things in this world, he will reign for three years and six months, and sit in the temple at Jerusalem; and then the Lord will come from heaven in the clouds, in the glory of the Father, sending this man and those who follow him into the lake of fire; but bringing in for the righteous the times of the kingdom, that is, the rest, the hallowed seventh day; and restoring to Abraham the promised inheritance, in which kingdom the Lord declared, that "many coming from the east and from the west should sit down with Abraham, Isaac, and Jacob." (Against Heresies, book 5.30.4)
There we go with that word fallacy operation Judaizers like to try and use against God's Word, in attempt to change the context of the Scripture. Greek 'naos' for the KJV word "temple" is the same word the Gospel uses when Jesus described the physical temple at Jerusalem.
Your doctrine on that sole word does not change it into always meaning the spiritual temple idea in Ephesians. Even with Paul's spiritual temple idea in Ephesians 2, it is still about the idea of a temple that is sacred, only it is applied in the spiritual sense there. One cannot just go slapping that connotation on every use of the word temple, for that is foolishness, and that's what you've tried to do.
Irenaeus' own words show he understood the "temple of God" in 2 Thess.2:4 as a literal physical temple in Jerusalem for the end.