St. Sophrony (Sakharov): Indifference to salvation

 The word accidie means, etymologically, 'lack of care', i.e., about one's salvation. With few exceptions, all humanity is not living in the state of accidie. People have become indifferent about their salvation. They do not seek divine life. They confine themselves to forms of life which appertain to the flesh, to everyday needs, to the passions of this world, to mundane activities. God, though, created us out of nothing, in the image of the Absolute and after His likeness. If this revelation is true, then the absence of concern for salvation is nothing else than the death of the human person.

+St. Sophrony (Sakharov), from Words of Life

St. Gregory Palamas: Life and Death of the Soul

This is real death, the soul's withdrawal from divine grace and its attachment to sin... this is the death from which to flee and of which to dread.... it is more dreadful than torment in Gehenna. That is why we flee it with our every power. We have cast out everything, left everything, renounced everyone, both relationships and business, and desires, that is, everything that destroys us and separates us from God and from everything out of which such a death exists. For one who fears and guards against this, the coming death of the flesh is not so terrible, for having real life in oneself, it moreover at death becomes unalterable from the person. For just as the death of the soul is real death, so too the life of the soul is real life. The life of the soul is its union with God, just as the life of the body is its union with the soul. And just as through the transgression of the commandment, the soul, being separated from God, was put to death; likewise its reunification with God, through obedience, grants it life. For this reason, the Lord said in the Gospels: "the words that I have spoken to you are spirit and life." (John 6:63) Learning this through experience Peter said to Him, that "You have the words of life." (John 6:68)  But "the words of eternal life" are for those who are obedient; to the disobedient this commandment of life brings death. (cf. Romans 7:10) For in the same manner the Apostles being an aroma of Christ, "were to one a fragrance from death to death, and to the other a fragrance from life to life." (2 Cor 2:16) 
+St. Gregory Palamas, from Treatise on the Spiritual Life, #2 The Life and Death of the Soul