ISB ~ 2 Thessalonians 2 v11

a strong delusion: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 (Is 6:9-10; 29:9-10). See note on Rom 1:24.

• Paul says “God will send” because, by his own just judgment, God will permit the devil to do these things. Being judged in this way, sinners will be deceived; and being deceived, they will be judged (St. Augustine, City of God 20, 19).