When the “man of lawlessness” comes he will deify himself, claiming to be God (2:4)
who opposes and exalts himself above every so-called god and object of worship, so as to seat himself in the temple of God, claiming that he is a god
He will dazzle the wicked with displays of his power (2:9). These are not miriacles ,which are the work of God, but illusions that make sinners think the poswer of God is being witnessed.
the one whose coming springs from the power of Satan in every mighty deed and in signs and wonders that lie,
He will decieve the world with falsehoods of every kind (2:10)
and in every wicked deceit for those who are perishing because they have not accepted the love of truth so that they may be saved.
God will respond to the wicked by worsening their problem. Because they will defy God and willfully reject the truth, he will permit them to love their evils and errors without the merciful restraint of his grace. (2:11-12)
Therefore, God is sending them a deceiving power so that they may believe the lie, that all who have not believed the truth but have approved wrongdoing may be condemned.
*“God will send” because, by his own judgment, God will permit the devil to do these things. Being judged in this way, sinners will be deceieved; and being deceived, they will be judged (St Augustine, *City of God **20, 19)