I also will choose their delusions, and will bring their fears upon them; because when I called, none did answer; when I spake, they did not hear: but they did evil before mine eyes, and chose that in which I delighted not.
Note closely in this verse that God did not create their delusion, only used it to serve a purpose.
And for this cause God shall send them strong delusion, that they should believe a lie:
In this case God sends a strong delusion. God has just cause to do that.
2 Thessalonians 2:9-10 English Standard Version
9 The coming of the lawless one is by the activity of Satan with all power and false signs and wonders, 10 and with all wicked deception for those who are perishing, because they refused to love the truth and so be saved.
In Isaiah 66:4 it was His children Israel. In 2 Thessalonians 2:11 it is people who have denied Christ.
If you have accepted Christ by faith you need not worry about being delusional.