Despair is a mortal sin. Flee from it. And believe in the Merciful God, our Mediatrix the Theotokos and the Saints. They can do all things. But it is absolutely necessary to humble oneself and be patient. St. Anatoly of Optina
A reader wrote and inquired about the above: why is despair was labeled a "mortal" sin? Isn’t sin, sin?
Here’s my reply:
I think the translator used the word “mortal” to emphasize the seriousness of the sin. Yes, sin is sin, you are correct there. However, despair can lead to suicide which is a “mortal” sin—the result being the taking of one’s own life. That certainly is very serious in the eyes of God and His Church.
Despair often points to a giving up of hope, of faith in a loving God and in the mercy of God. Those feelings can move a person to take their fate into their own hands. May God grant that none of us fall into despair, but rather cling to the hem of His garment at all times.