Who opposes and exalts himself above all that is called God, or that is worshiped; so that he as God sits in the temple of God, showing himself that he is God.
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Cyril of Jerusalem
AD 386
so much so that he sits in the temple of God
he means, the Temple of the Jews which has been destroyed. For if the Antichrist comes to the Jews as Christ, and desires to be worshipped by the Jews, he will make great account of the Temple, that he may more completely beguile them; making it supposed that he is the man of the race of David, who shall build up the Temple which was erected by Solomon.