Masturbation, genital activity alone or with another person that does not result in sexual intercourse, is also a sin agaisnt chastity. It is all about pleasure without regard for life or real love. Sins agaisnt chastity include other forms of genital sexual activity that stop short of sexual intercourse, such as petting or oral sex. They are forms of exploitation, and are not appropiate sexual expressions for semicommited love. These activities can also prevent true intimacy in future relationships

Masturbation: Self manipulation of one's sexual organs for the purpose of erotic pleasure or to achieve orgasm. The Church considers masturbation a sin because the act cannot result in the creation of life. It is also wrong because it is self-serving, and God created sex not for self-gratification but to unify a husband and wife in marriage.

well according to that definition, condoms are a sin also, because "it cannot result in the creation of life" so thats stupid. according to that every time we have sex it should be for a baby. 

Offenses against chastity

2351 Lust 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.

2352 By masturbation is to be understood the deliberate stimulation of the genital organs in order to derive sexual pleasure. "Both the Magisterium of the Church, in the course of a constant tradition, and the moral sense of the faithful have been in no doubt and have firmly maintained that masturbation is an intrinsically and gravely disordered action."137 "The deliberate use of the sexual faculty, for whatever reason, outside of marriage is essentially contrary to its purpose." For here sexual pleasure is sought outside of "the sexual relationship which is demanded by the moral order and in which the total meaning of mutual self-giving and human procreation in the context of true love is achieved."138

To form an equitable judgment about the subjects' moral responsibility and to guide pastoral action, one must take into account the affective immaturity, force of acquired habit, conditions of anxiety or other psychological or social factors that lessen, if not even reduce to a minimum, moral culpability.

2353 Fornication is carnal union between an unmarried man and an unmarried woman. It is gravely contrary to the dignity of persons and of human sexuality which is naturally ordered to the good of spouses and the generation and education of children. Moreover, it is a grave scandal when there is corruption of the young.

2354 Pornography consists in removing real or simulated sexual acts from the intimacy of the partners, in order to display them deliberately to third parties. It offends against chastity because it perverts the conjugal act, the intimate giving of spouses to each other. It does grave injury to the dignity of its participants (actors, vendors, the public), since each one becomes an object of base pleasure and illicit profit for others. It immerses all who are involved in the illusion of a fantasy world. It is a grave offense. Civil authorities should prevent the production and distribution of pornographic materials.

If you do not confess your sin before you die, you will go to hell. Please, go to confession and don't sin anymore.

that's not true... (or the part about going to hell)
but that's funny.
anyways, we have alot of concrete evidence that masturbation is a sin..

will this topic ever end!?

Masturbation is mostly a venial sin, not truly mortal.. unless you let it be.. and you are doing in on purpose and what not

Venial or Mortal, it's still a sin.

Usually before you die, you can confess your sins for the last time and if you don't... when people pray for you when you die, they are helping you get into heaven because it's not something your spirit can't do without help of others

Notice the words "grave" sin. This falls under mortal sin if you knew it was a grave sin and you did it by your consent.

lol.. now ur catching on...

I hope to God it's not.

...seriosuly, the thought scares me.

ooooooo. j00 going to heeeell!

He never said HE masterbates.

To me, no, it's not a sin. I don't understand why it is to some Christians. I've heard that it's like ending possible lives, but then some others say that it isn't because they were never fertilized?

Iono.

I could see why sex before marriage is a sin {Even though I don't think it is.}, because it's supposed to be used for creating new people, not sexual pleasure. But why would God give us masterbation and tell us not to use it? It won't help us have children..I don't see any other purpose for it except to relieve us..if anything, I think Christians should applaud masterbation because it would help us refrain from having sex until we're married.

There really needs to stop being so many restrictions.