What is lukewarmness and is it a mortal sin?

The following definition is given in the New Catholic Encyclopedia, “Lukewarmness or tepidity, in spiritual theology, signifies the state of soul to which the warmth and fervor of charity is wanting, but has not yet completely deteriorated into the coldness of indifference and hatred.” In this understanding, lukewarmness would not be a mortal sin as such, but can eventually (and quickly) lead to mortal sin.

The lukewarm soul tends to neglect the duties of its state in life. To always strive for the bare minimum fulfillment of temporal and spiritual commitments is to be lukewarm. In the book of Revelation Our Lord says to the Laodicean church, “I know your works; I know that you are neither cold nor hot. I wish you were either cold or hot. So, because you are lukewarm, neither hot nor cold, I will spit you out of my mouth”( 3:15-16). Here Christ reminds us that if we are not going forward in the spiritual life, we are going backwards.

The Diary of Saint Faustina has this to say about the lukewarm:

“There are souls who thwart My efforts (1682). Souls without love or devotion, souls full of egoism and selfishness, proud and arrogant souls full of deceit and hypocrisy, lukewarm souls who have just enough warmth to keep themselves alive: My Heart cannot bear this. All the graces I pour out upon them flow off them as off the face of a rock. I cannot stand them because they are neither good nor bad (1702)…My soul suffered the most dreadful loathing in the Garden of Olives because of lukewarm souls. They were the reason I cried out: “Father, take this cup away from Me, if it be Your will.” For them, the last hope of salvation is to flee to My mercy.”

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