Why is lust a sin in Christianity?

Answer 1

Lust [as in intense or unbridled sexual desire] is the urge to engage in the sex act for pleasure. It is a sin because the true purpose of the sex act is procreation, not pleasure. To engage in intercourse for purposes other than procreation is to love self inordinately, above God. This is the "Original sin" of Adam and Eve: engaging in intercourse to pleasure selves/each other rather than to procreate. Hence, they covered their "loins" in shame, not their mouths, which they might have done had they eaten apples---which were not in existence at that time. Persons campaigning against same-sex marriage, or even togetherness, seem to conveniently forget the part about procreation when they introduce God into their argument/rant.

Roman Catholic AnswerLust is disordered desire for or inordinate enjoyment of sexual pleasure. Sexual pleasure is morally disordered when sought for itself, isolated from its procreative and unitive purposes. from the Catechism of the Catholic Church

In other words, marriage is created for two purposes: procreation and the love between husband and wife. ANY desires or sex outside of those two purposes in a marriage is disordered and sinful. Human beings are created by God to be pure, to be chaste. Jesus said, "You have heard that it was said, 'You shall not commit adultery.' But I say to you that everyone who looks at a woman lustfully has already committed adultery with her in his heart. The tradition of the Church has understood the sixth commandment (You shall not commit adultery) as encompassing the whole of human sexuality. Human beings are to be chaste and pure for the Kingdom of God.

There are seven "deadly Sins". These are sins which are the mothers of other sins, they are the root of all sins:

Pride

Greed

Lust

Anger

Gluttony

Envy

Sloth

So, yes, lust is one of the seven deadly sins, meaning that it 1) is a mortal sin (it completely kills the soul; unconfessed, it is a one way ticket to hell, complete separation from God and eternal agony) and 2) it is the mother of other sins.

Answer 2

Lust is a sin because lust is when you want to have sex with someone other then a spouse. The Bible says that you are committing adultery if you think about having sex with someone you are not married to, even if you are not married.

Answer:

First of all, the Bible defines "sin" as "...the transgression of the law." [I John 3:4].

And the 10th law of God; the 10th Commandment, is about lusting.

"...for I had not known LUST, except the law had said, Thou shalt not covet." (Rom.7:7)

Lust is more than "illicit sex." Like the rest of God's laws... lust is "spiritual":

"For we know that the law is spiritual..." (verse 14).

The sinful acts that men do begin with a "thought." Thinking is "spiritual."

Lust is a powerful "emotion" [spirit] that DISRESPECTSthe one lusting... and those at whom one's lust is aimed... and who are hurt by the actions that follow and fulfill the lustful thought.

Lust leads to the breaking of the rest of the Commandments. Lusting after someone else's possessions leads to theft; the transgression [breaking] of Commandment 8. It leads to adultery; #7. It leads to lying; #9.

Lust is basically at the root of all 10 "sins" -- the transgression of the law. The emotion leads to the act.

That's why we need to "walk in the Spirit of Christ" -- which is the "GUARDING OF ONE'S THOUGHTS."

"If you keep on biting and devouring each other, watch out or you will be destroyed by each other. So I say, Live by the Spirit, and you will not gratify the desires of the sinful nature. For the sinful nature desires what is contrary to the Spirit, and the Spirit what is contrary to the sinful nature. They are in conflict with each other, so that you do not do what you want. But if you are led by the Spirit, you are not under the law.

"The acts of the sinful nature are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissentions, factions and envy; drunkenness, orgies, and the like. I warn you, as I did before, that those who live like this will not inherit the Kingdom of God." (Gal.5:15-21 NIV)

Giving in to the "sinful nature," lust [denying Jesus Christ] deprives us of Christ, Eternal Life and the Kingdom of God.

Lust is the nature of the flesh -- WHICH IS CONTRARY TO THE SPIRIT OF GOD; the fruits of which are:

"...Love, Joy, Peace, Patience, Kindness, Goodness, Faithfulness, Gentleness and Self-Control. Against such things THERE IS NO LAW." (verses 22-23)

There's no law against "obeying the law." There's no law against not murdering someone. No law against not stealing. No law against not lying. No law against not committing adultery. No law against not lusting. No law against respecting your parents. No law against not worshiping false gods. No law against worshiping the True Eternal Creator of man and the universe [who is Jesus Christ, the WORD of God - John 1:3].

"The mind of sinful man is death, but the mind controlledby the Spirit is Life and Peace [unfortunate NIV translation; it should be 'led'; the Holy Spirit "leads" and "guides." Demon possession "controls"]; the sinful mind is hostile to God. It does not submit to God's law, nor can it do so..." (Rom.8:6-7 NIV).

It's because the world transgresses all these laws and is lost in its lusts, that it's "devouring itself."

Lusting isn't just a "sin in Christianity." Lust is killing Muslims, Hindus, Taoists, Shintoists, Buddhists... millions of believers of hundreds of other false religions... and atheists, too. Because lust is a deadly matter of the errant "human spirit" -- the natural, carnal, selfish human mind in all men -- not the tenets of one religion.