Pornography. At first glance, the practice of such things seems rather grotesque. Pictures or movies or cartoons showing the parts of peoples' bodies that their bathing suit should cover all the while performing an act, the likes of which should only take place in the context of the marital bed. Even then so, much of what is shown in such pictures, videos, and cartoons would be considered sinful, even within that context; However, that is its own article to be written in the near future.
Just as those pornographic forms of media may be perceived as grotesque by those unfamiliar with such things, it is deemed equally grotesque in the eyes of God. Despite this, many people nowadays consider such pornographic medias to be healthy due to it impacts on controlling sexual urges in many people, so long as it is in moderation, and unless it is in moderation many people, especially men-- may experience low testosterone levels (which is a bad thing) as well as sexual impotence (pornography is the leading cause of E.D. in men under 24). This is especially true in men who use pornography as a substitute for human contact, or even a freely available substitute for sexual education.
Pornography as a social issue is mainly in regards to those people (both men and women) who deal with this issue on a regular basis. The effects that pornography has on a person are as follows: An over-stimulation of the brain, leading to chemical reactions commonly found in drug addicts, with a heavier kick than cocaine, might I add; A domino effect that can lead a person toward a myriad of sexual fetishes and by extension, relying on them to gain the same effect that they once received from (for lack of a better word) cleaner forms of pornography. Just as a drug addict will eventually need to take more of the substance due to a building tolerance for it, the pornography addict will eventually rely on filthier, and in some cases darker forms of pornography over time to achieve the same effects, eventually getting bored and moving onto the next available form of pornography (whether it is legal or illegal depends on the addict).
The content found in much of mainstream pornography, is also detrimental to the formation of relationships, whether it is in the case of dating, marriage, friendships, etc. due to the fact that, if a male or female has consumed pornography from a young age, and it served as the sole education they have, or the only familiarity they have on the subject of intimacy, their perceptions of intimacy will reflect on the content of the pornography they consume. In this regard they become more selfish and less generous, they become less willing to socialize and place more priority on the high they receive from viewing pornography, similar to the actions of the standard substance abuser.
As a religious issue, however, the issue of pornography is multiple sins wrapped in a single category, that being one of the seven deadly sins: Lust. With regards to what sins are committed by pornography, they can be separated into two groups: the consumer and the pornographer. We'll start with the consumer.
The sins committed by the consumer are mortal (purposeful) sins and are as follows: Covetousness (desiring person or a thing that is not theirs (or meant to be theirs) and for it to come into their possession), Lust as an offspring of envy, desiring something specific which is someone else's or meant for someone else that will never come into their possession, Adultery (aka cheating) as you are viewing someone other than your spouse or potential spouse or someone else's spouse or potential spouse as a sexual partner. Self-gratification is also a sin in the case that such actions are a withholding from ones spouse or future spouse for the sake of yielding to one's own selfish desires (otherwise known as incontinence). In the case of the pornographers themselves, they are guilty of Scandal (the opposite of modesty that can lead others into sin (or the near occasions of sin)). In addition, they are also guilty of fornication, the solicitation of sin, prostitution (the solicitation of sex for money) and incontinence (lack of self-restraint) as well as adultery.
To those I've categorized as consumers who struggle with such sins to the point of habitual addiction, I say this: It is completely possible to overcome such things as well as reaching the point where such things are feeble, temporary stimulations, in comparison to the spiritual rewards provided in the eternal sanctuary of heaven. However, it is impossible to overcome this addiction cold turkey without assistance. That is assistance from both God and supportive friends. In the words of Saint Pope John-Paul II:
"The only way to overcome a secular evil is with a spiritual good"
In that respect, Pornography is indeed evil and has always been and always will be considered a plague upon both the faithful and all mankind.
And as for those categorized as pornographers, If you somehow find it in your hearts to repent of the sins mentioned above, please, for the love of God, petition those that published that material to both remove it, destroy it and damn it to the depths of hell where it belongs. That, along with a significant amount of prayer begging for God's forgiveness and a significant amount of regret and humility in regards thereto. Then and only then, can you be wholly repentant of those sins. But even then so, the final judgment is solely up to God himself and may he have mercy on your souls.