I'd say that negative attitudes about women and a belief in traditional gender roles (and the belief that 1. gay men are effeminate, and 2. that it's bad for men to be effeminate). Plus there's that possible fear some men may have that gay men will treat them the way they themselves treat women (aka like objects).
The rigid gender role thing bears more investigation as a cause for at least some instances, I think.
I agree that this is a major factor.
I think this also ties into fear of not having sexual control, or not having one's desires catered to.
I think it plays into homophobia against gay women, as well, particularly when it's perpetuated by straight men. Homophobia against lesbians often seems based on the view of women as sex objects. Lesbians in porn are "good" because they're providing titillation, but I think real lesbians are often seen as a threat because they don't appreciate or accept advances from men--and I think a lot of homophobic and sexist men are threatened by sexual expression that doesn't directly benefit them or isn't in their control.
Some of the
reactions when the Dragon Age games included the possibility of allowing a male character to have a relationship with another man really made an impression on me. The basic tone of the outcry was that the games should cater to straight men by allowing them to only see romantic or sexual content that they can relate to or find titillating.
I think that's a common attitude among homophobic and sexist straight men--the idea that sexuality is for
them.
(Of course, there is homophobia in other demographics as well. But I think misogyny can play a large role in general.)
There's a difference between the "rank and file" and the "leadership," between people who simply happen to think homosexuality is wrong and people who invest a lot of emotional energy in it. I suspect the latter category contains a higher percentage (though not 100%) of closeted people than the former. For one thing, I suspect people who start out in the rank and file but recognize those urges in themselves are inspired to put a lot of emotional energy into it.
I tend to agree. When someone is extremely invested in an issue, sometimes there's a reason. Also, some of the strongest tirades against homosexuality that I've seen have been
extremely focused on sex. I don't think that always suggests that the person is gay, but it does suggest a fixation on sex, and maybe gay sex in particular.