Homophobia (homo = same, phobia = fear) is never used according to its etymological meaning, fear of sameness. In its broader sense homophobia simply refers to disapproval of homosexuality. It is also used to mean hatred and fear of homosexuality or homosexuals themselves.
Often the point is made by some homosexuality advocates and their sympathizers that the distinction is a narrow one. Thus the term is used variously to mean any sort of disapproval of homosexuality, whether subtle or explicit, unconscious or conscious, completely unreasoning or in some way principled.
Religious groups and some others labelled homophobic strongly deny that their disapproval of homosexuality, often based on their interpretation of religious scripture or principles, is informed by "fear and hatred", while they are forthright in their moral disapprobation. They claim that the terms homophobia and homophobic are used to blur the difference between those who actively fear and loathe homosexuals and those who merely disapprove of homosexuality on principled or religious grounds, in order to shame the latter into abandoning their disapproval.
Gay rights activists counterargue by saying that it is not believing homosexuality to be wrong which constitutes homophobia, but rather specific positions and actions such as opposing equal rights and protections for gay people. However, opposition to equal rights protections, gay marriage, and hate crimes legislation is often informed by religions beliefs. Most gay rights activists say that the believing homosexuality to be sinful is not incompatible with support for gay rights legislation, as it is in the spirit of the religious philosophy of "hate the sin; love the sinner" and the Biblical injunction to "judge not, lest ye be judged" (Matthew 7:1). The majority of gay rights activists support religious freedoms and the right of religious persons to hold their views, but say those beliefs should not be allowed to adversely influence their position as equal citizens under the law. Religious opponents of gay rights laws, however, believe that supporting pro-gay legislation would constitute approval of homosexuality itself, something which is incompatible with their faith.
Many religious organizations and denominations do in fact support gay rights and oppose homophobia. The Metropolitan Community Church is a Protestant Christian denomination with a predominantly gay membership which includes support for gay rights within its theology. Another prominent denomination supporting gay rights is Unitarian Universalism, which ordains gay and lesbian ministers and has a formal program in place for recognizing congregations that welcome and embrace gay people (a "welcoming congregation"). Many divisions of Judaism also reject homophobia, as do many divisions of Quakerism.
However the term is understood, homophobic beliefs and attitudes can be held by people independent of their sexuality. In lesbians, gays and bisexuals internalised homophobia can result in lifelong suffering of depression, low self-esteem and a stunted love life and sexuality. Some psychologists and psychiatrists attribute the much higher incidence of suicide among gay teenagers as due to this, although others believe it is due to homophobic actions against them, such as namecalling, ostracization (particularly by their family), and other harassment.
Extreme cases of homophobia have resulted in cases of murder in the United States (see hate crime) in which a person was killed due to their perceived homosexuality, although in some cases is it not at all clear the person was actually homosexual. In some of these cases, the defendant argued that their action was due to a moment of panic because they believed the victim was "coming on to them". This phenomenon is generally referred to in the gay community as the "gay panic defense".
Murder of course is the most extreme manifestation of homophobia, and occurs relatively infrequently. Much more common are cases of nonfatal beatings, shootings, stabbings, and so on. Fear of physical violence is widespread among homosexuals, and many of them migrate to urban areas both for the safety and cultural advantages large gay communities offer them. Even urban environments are not always safe, as it is not unknown for gangs of youths to travel into gay communities in search of targets.
Most often, homophobia manifests itself in discrimination. Up until very recent days, discrimination against homosexuals was widespread, and it still is in some areas, particularly rural areas. Many homosexuals are fired from their jobs, denied housing, and harrassed in various ways.
The cause of homophobia in society has been widely debated.
Some religious organisations and individuals actively oppose homosexuality, which--depending on one's definition of "homophobia"--can either directly or indirectly foster homophobia. Some religions will not ordain those lesbians and gays who have come out of the closet.
Some gender theorists interpret the fact that male/male activities or relationships often incites a stronger reaction in homophobics than female/female (Lesbian) activities or relationships as meaning that the homophobic feels threatened by the subversion of the gender paradigm in male/male sex. Homophobics often express strongly sexist views and tend to focus on the sexuality of lesbigay people to the exclusion of all other traits, in much the same way as racists tend to define people exclusively by their ethnicity.