2 Thessalonians 2:10-12 - Delusions from Rejecting Truth.

Those who do not love the truth, which is their only defense,
will be swept away by all kinds of deceptions brought about by the
power of evil.  Because of this, they have no protection against these
delusions and will end up believing a lie.  However, they will not be
judged because they believed a lie but because they did not believe the
truth and continued to take pleasure in wickedness.
2 Th 2:10-12 (CWB)

God gives people freedom to turn their backs on him and believe
Satan's lies. If they say no to the truth, they will experience the
consequences of their sin. [Life Application SB]

They did not love the truth, and therefore did not believe it;
and they were pleased with false notions. God leaves them to
themselves, then sin will follow of course, and spiritual judgments here,
and eternal punishments hereafter. (Matthew Henry's Commentary)

The belief of the truth brings the sinner to rely on Christ, and
so to love and obey him; it is sealed by the Holy Spirit upon his
heart. (Matthew Henry's Commentary)

Those who are unwilling to accept the plain, cutting truths of
the Bible are continually seeking for pleasing fables that will
quiet the conscience. The less spiritual, self-denying, and
humiliating the doctrines presented, the greater the favor with which they
are received. These persons degrade the intellectual powers to serve
their carnal desires. Too wise in their own conceit to search the
Scriptures with contrition of soul and earnest prayer for divine guidance,
they have no shield from delusion. Satan is ready to supply the
heart's desire, and he palms off his deceptions in the place of truth.