You say an insurmountable, inexplicable sadness torments you. Physically you are healthy, your house is full, but your heart is desert. In fact your heart is full of a dark sadness. You go out of duty to entertainments and shows but this increases your sadness even more. Guard yourself; this is a dangerous spiritual sickness. It can completely kill the soul. The church regards such sadness as a deadly sin – because according to the words of the Apostle there are two kinds of sadness: sadness after God, which brings repentance for salvation and the sadness of this world, which brings death. In your case is obvious is the second kind of sadness.
The sadness after God comes over the man when this one remembers his sins and repents and cries to God or when someone is sad because of the sins of the others, or when someone has zeal for the faith in God and sees sadly how the men fall from faith. God changes this sadness into joy.
It is exactly how saint Paul the Apostle describes the apostles and all the true servants of Crist saying they are like sad people but in the same time they rejoice. They rejoice because they feel the power and the closeness of God. They receive comfort from God. This is what the psalmist says: `I remembered God and rejoiced.` The sadness of the saints is like some clouds through which shines the sun of comfort. – your sadness is like a sun eclipse.
There must have been many small sins and villain deeds which you considered as insignificant and you did not confess and did not repent for them. Like an old cobweb they thickened around your soul and they became like a nest for your great sadness which the evil demonic power maintains with malicious satisfaction in you.
For this reason search your entire life, make a critical analyze to it and confess everything at confession. By confession you will clean up and ventilate the house of your soul. The fresh and healthy air coming from the Spirit of God will come inside you. After that start doing bravely what is good. Start let`s say with the alms in the name of Christ. Remember: `In the name of Christ`. Christ will see and feel this and He will immediately give you a joy, He will give you an inexpressible joy, joy which is given only by Him and which no sadness or torment or devilish power can ever darken. Read the Psalter. This is the book for the saddened souls, the book of solace.
May God make you joyful soon!
Excerpt from Answers at questions of the world from nowadays – Missionary letters– Saint Nicholas Velimirovich, Sophia Publishing.