Bible Dictionary
DELUSION
Delusion is error, deception, or wandering from the truth. Scripture may use the term for human folly and for the judicial working of error experienced by those who reject the truth.
Biblical Usage
Isaiah 66:4 uses the word in an ambiguous expression that may mean wantonness, caprice, mockings, insults, or follies. In 2 Thessalonians 2:11 it describes a working of error, literally a wandering or roaming about, affecting those who do not receive the truth.