Prelest (from Church Slavonic: пре́лесть, itself from Church Slavonic: лесть, romanized: lestʹ, lit. 'charm, seduction, cajolery', IPA: [lʲesʲtʲ] ; Medieval Greek: πλάνη, romanized: pláni, lit. 'wandering astray; fallacy', IPA: [ˈpla.ni]), also known as spiritual delusion, spiritual deception, or spiritual illusion, is an Eastern Orthodox Christian term referring to a false spiritual state of holiness or a spiritual illness of believing oneself less sinful than one is.
Prelest should not be confused with mental illness, and is instead considered a spiritual illness that originates from vainglory, pride, and demonic suggestion. It is said to be cured by humility and the Holy Sacraments and under the guidance of the spiritual father.[1] In a broad interpretation, everyone is considered to be in prelest, as everyone has some wrong thoughts and views, do not fully understand the meaning of life and the degree of their own sinfulness.
When used in a narrow sense, meaning that some particular person is in the state of prelest, it usually means that a person, initially being on the path of a pious Christian life, instead has become prideful and self-conceited about their own personal sanctity, believing themselves less sinful than they are. In Eastern Orthodox thought, the closer a person is to God, the more they see their imperfection, and all true saints considered themselves in the feeling of the heart the greatest sinners. The state opposite to prelest is spiritual sobriety.