Opposition to pornography
Reasons for opposition to pornography include religious objections, feminist concerns, and claims of harmful effects, such as pornography addiction. Anti-pornography movements have allied disparate social activists in opposition to pornography, from social conservatives to harm reduction advocates.

The definition of "pornography" varies between countries and movements, and many make distinctions between pornography, which they oppose, and erotica, which they consider acceptable. Sometimes opposition will deem certain forms of pornography more or less harmful, while others draw no such distinctions.

A 2013 Gallup survey reported that, of U.S. adults, 66% believe that pornography is "morally wrong" while 31% believe that it is "morally acceptable". The gender gap in pornography opposition has widened in the recent decades; women remain more opposed to pornography than men, while men's opposition has declined faster.

Religious views

Most world religions have positions in opposition to pornography from a variety of rationales, including concerns about modesty, human dignity, chastity and other virtues. There are numerous verses in the Bible which are cited as condemning pornography or adultery, notably for Christians, Matthew 5:28 in the Sermon on the Mount which states "that anyone who looks at a woman lustfully has already committed adultery with her in his heart." Islam also forbids adultery, and various verses of the Quran have been cited as condemning pornography, including Quran 24:31 which tells men to "restrain their eyes" from looking sexually at women.

Feminist views

Some feminists are opposed to pornography, arguing that it is an industry which exploits women and is complicit in violence against women, both in its production (where they charge that abuse and exploitation of women performing in pornography is rampant) and in its consumption (where they charge that pornography eroticizes the domination, humiliation, and coercion of women, and reinforces sexual and cultural attitudes that are complicit in rape and sexual harassment). They charge that pornography contributes to the male-centered objectification of women and thus to sexism.

However, many other feminists are opposed to censorship, and have argued against the introduction of anti-porn legislation in the United States - among them Betty Friedan, Kate Millett, Karen DeCrow, Wendy Kaminer and Jamaica Kincaid. Some sex-positive feminists actively support pornography that depicts female sexuality in a positive way, without objectifying or demeaning women.

Conservative views 
Religious conservatives commonly oppose pornography, along with a subset of feminists, though their reasoning may differ. Many religious conservatives view pornography as a threat to children. Some conservative Protestants oppose pornography because it encourages non-procreative sex, encourages abortion, and can be connected to the rise of sexually transmitted diseases.

Concerned Women For America (CWA) is a conservative organization that opposes same-sex marriage and abortion. When discussing violence against women, the CWA often uses pornography to illustrate their points. The CWA asserts that pornography is a major reason why men inflict harm on women. The CWA argues that pornography convinces men to disrespect their wives and neglect their marriages, thereby threatening the sanctity of traditional marriage. Unlike other issues CWA has tackled, they are less forcefully anti-feminist when it comes to the topic of pornography, as many of their points surrounding why pornography is distasteful parallels those of anti-pornography feminists.

Harm-based views

Dolf Zillmann argued in the 1986 publication "Effects of Prolonged Consumption of Pornography" that extensive viewing of pornographic material produces many unfavorable sociological effects, including a decreased respect for long-term monogamous relationships, and an attenuated desire for procreation. He describes the theoretical basis of these experimental findings:The values expressed in pornography clash so obviously with the family concept, and they potentially undermine the traditional values that favor marriage, family, and children... Pornographic scripts dwell on sexual engagements of parties who have just met, who are in no way attached or committed to each other, and who will part shortly, never to meet again... Sexual gratification in pornography is not a function of emotional attachment, of kindness, of caring, and especially not of continuance of the relationship, as such continuance would translate into responsibilities, curtailments, and costs...

A study by Zillman in 1982 also indicated that prolonged exposure to pornography desensitized both men and women toward victims of sexual violence. After being shown pornographic movies, test subjects were asked to judge an appropriate punishment for a rapist. The test subjects recommended incarceration terms that were significantly more lenient than those recommended by control subjects who had not watched pornography.

Some researchers like Zillman believe that pornography causes unequivocal harm to society by increasing rates of sexual assault. Other researchers believe that there is a correlation between pornography and a decrease of sex crimes.

Pornography is often criticized for presenting an inaccurate picture of human sexuality.

The appropriation of the sexually explicit in American culture is part of what has been called "the pornification of America".

Rape culture is often discussed when it comes to pornography, and is defined by society victim-blaming women because of their rape. It is known as society making rape less substantial. Some of the most searched titles on pornography websites is rape scenes.

Allegations of pornophobia

Pornophobia, from Greek roots pornē, "whore" and phobia, literally means fear of prostitutes. It may also refer to fear of sexual expression, in particular, fear of pornography. 

Nadine Strossen, former president of the American Civil Liberties Union, uses the coinages "pornophobia" and "pornophobes" when referring to attitudes of pro-censorship and conservatives to the imagery of nudity, which they often refer to as "pornography". Strossen states that incidents have occurred at several colleges such as the University of Arizona and the University of Michigan Law School where feminist students have physically attacked exhibits of photographic self-portraits claiming that they must be taken down because these exhibits had sexual themes.