Lust Dulls the Spiritual Senses
"...every one who looks at a woman lustfully has already committed adultery with her in his heart." - Jesus Christ (Mt 5:28)
"Can a man take fire to his bosom and his garments not be burned?" - Proverbs 6:27
"Lust is disordered desire for or inordinate enjoyment of sexual pleasure." - The Catechism of the Catholic Church, #2351
To be fair, there is one good thing about the sin of Lust: it cannot persist into eternity. In actuality, sins of the flesh tend to burn themselves out over time. After a while lust becomes a habit and what pleasure it brought diminishes until we wonder what the attraction is.
We can limit lust to sexuality, but we may want to consider the larger area of sensuality. Sensuality is the craving for physical pleasures of all kinds. An inordinate desire to avoid pain, for physical and even emotional comfort, the best food and wine, the best looking car, can all be forms of lust. Lust denies our spiritual nature and promotes the lie that "this is all there is." We try to make a heaven on earth, but instead we create a hell. Other people become ways of satisfying our needs. They are merely objects to service us, bring us food, run our business, give us pleasure. We want to reduce the population of the world so we won't have to share or we want more children so they can carry on the family business. Everyone else becomes a means to an end.
Still, we usually think of lust as it pertains to sexuality. It is good to clear up a few misconceptions about the Christian view, at least as it is put forth by the Catholic Church:
In marriage, enjoyment is not the problem. Lust enters into marriage when sex is not a mutual expression of love, but rather the use of one person by another (even if the "use" is mutual). This, of course, breeds resentment and eventual alienation, even if the couple do not separate.
Another misconception is that Christians are obsessed with Lust. While this may be true for some individuals, the Church simply applies the same rules to sex that we apply to everything else: all things must be made subject to the will of God, as revealed by Jesus Christ. There are correct times and places for many things in life ("To everything there is a season"). We simply state that sex is not an exception. Money, power, sex, reputation/honor or individualism can all become obsessions and even gods to us, but they are not evil in themselves.
Update - Professor Simon Blackburn, of Cambridge, is among the academics who assert that lust is a virtue. Let us examine his logic: Thirst is not considered sin, but thirst can lead to drunkeness, so lust should not be condemned. Intelligence tests given to children have questions like, "horse is to rider as car is to ______." Clearly, this professor would fail such a test. Thirst is to drunkeness as sexual urges are to lust (or immoral sexual acts). If he meant "sexual urges," those powerful but God-created guarantees of humans in perpetuity, he should have said so. Not only is the professor pandering to what people want to hear, he is also careless with words and concepts, and as a philosopher, he should know better. It is always essential that a philosopher uses the exact language demanded, and he failed to do so. His second error is the presumption that pleasure is enough. Pleasure is not enough. It is a spice of life, but so are accomplishment, peace of mind, curiosity and inquiry, good conversation, and play. Lust is by its nature disordered, and contributes to the dukkha, the disjointedness of the world as each person pursues their pleasure. It is sad to think Cambridge has fallen so far.
Lust blinds us. In dating, lust causes us to miss the warning signs in the relationship. We gloss over major obstacles to a good marriage because our physical desires are driving us. Lust is enslavement to the senses, to the animal part of man. Lust deadens our spiritual senses so we cannot hear God calling. If you are professing to be a Christian and yet are fornicating or committing adultery (these mean sexual contact or pleasure, not just intercourse, outside of marriage), you are fooling yourself. Unrepented lust is a solid barrier to growth in faith, but it does not prevent growth in Pride. Think about it.
For some people, meditating on death and the grave may help control the sexual drives. Not out of fear, but from a simple realization that this life doesn't last forever. The present body is corruptible, the next body is glorious. Let us keep our "eyes on the prize," and not on this fleeting life in feeble flesh.
For continued reading, the following are a few good books:
"Mere Christianity," by C.S. Lewis
"Prayers," by Michel Quoist
"The Cost of Discipleship," by Dietrich Bonhoeffer