Searing words from Vladimir Solovyev's masterpiece, God, Man and the Church: The Spiritual Foundations of Life:
Self-love is the father of all deceit, its cunning sophistries beguile our understanding and lead to two disasters: it weakens man’s will in the fight with temptation, and it hands over his soul in advance to all kinds of iniquity. The unscrupulous selfish man does not merely spoil himself morally by committing such and such sins from time to time: he is completely deprived of stability and moral behavior and his whole life is one long sin; he is inevitably unjust in his dealings with others and his personal desires are endless. There is a vitality of immense vigor in all of us, and if it be captured by egoism there is no satisfying it. Disappointment of inordinate wants begets resentment, whose impotent anger leads to discouragement and discouragement to despair – the logical end of an over-ruling self-love is madness or suicide; and those suffering from this moral sickness who stop short of such an end should thank the mercy of God and the prayers of their friends.Here is Solovyev on the connection between the practical duties of religious life and the three "theological" virtues:
Prayer, alms-deeds and fasting are the three fundamental works of individual religious life, the corner-stones of personal religion. He who neither prays to God nor helps his fellows nor subdues his appetites is not a religious man, even though he may have thought, talked and written about religious subjects all his life. These three things are so closely connected that no one of them has efficacy without the other two. If prayer does not lead to alms-giving and self-denial it is bad and useless, vitiated by partiality and self-esteem, it is not prayer at all; alms which are not a fruit of prayer and joined to temperance are an expression of weakness of character rather than of love, sincere alms-giving is the highest justice and must lean upon heavenly grace; fasting undertaken from vanity or from egoism, as an exercise in self-control, may give strength but it is not strength for goodness, and fasting without generosity (even though prayer be joined to it) is the sacrifice of which it is said, "I will have mercy and not sacrifice." It is the union of all three activities that enables divine grace to be effective, and that grace does not stop at joining us with God in prayer, it assimilates us, in charity and in temperance, to the all-merciful and all-sufficient Godhead.Solovyev's book is the finest modern apologetic for Christianity I've ever encountered. Highly recommended.
The three basic religious works are also fundamental duties. We are bound to do only so much as we are able, and it is beyond man's powers to unite himself with the Godhead completely, to save mankind, or to redeem the whole of nature: therefore religion does not tell each one of us personally to do these things. But it is in our power to pray to God, to help those we know to be in trouble, and to fashion our own nature by temperance – and those are the personal duties of every man and woman.
In the discharge of these religious obligations are objectified the three God-regarding virtues: Prayer to God in faith; well-doing towards men in love; control of natural appetite in hope of the coming resurrection.