“And for this cause God shall send them strong delusion, that they should believe a lie: That they all might be damned who believed not the truth, but had pleasure in unrighteousness.” 2 Thess 2:11-12
The delusion is that one can continue to sin and still receive eternal life which causes the person to never truly repent and therefore be damned.
"...that they should believe a lie"
The Greek text reads "that they should believe THE lie."
They believe the great lie of Satan - the lie he told Eve - that she could disobey God and "Ye shall not surely die".
Harold and Donna Kupp