I was browsing through the archives of Reformation Theology (a web blog managed by a group of reverends and others) when I found an article (in the “Social Commentary” category) which talks about responses to the Roman Catholic church’s (now old) document that officially prohibits gays from becoming priests or entering seminary. If you are too lazy to read the article in its full and long-ish glory, at least read this excerpt I found particularly good for serving the purposes in mind.
It all boils down to the desire to be gods for ourselves, to justify ourselves, to rebel against any authority that would seem to place itself over us (especially religious authority). When someone wants to believe that something is permissible, right, or good, and someone comes along telling him that God, the Bible, or the Church is in direct opposition to that view, he becomes much more sensitive to the fact that his autonomous self-authority is being called into question. He’s faced with the idea that maybe he’s not okay just because he says so. God, the Bible, or the Church says otherwise, which he instinctively perceives as a threat, and becomes vocal in his rebellious self-justification, questioning the appropriateness of the authority that challenges him. The fellow who normally feels pretty solid in his worldview that has himself as god has to scratch and claw for a bit to retain his position in his false reality.