Adulterers were to be stoned in the Old Testament. How many of these people would do that? Clearly they fail to understand Christianity if they take it upon themselves to inflict punishments.
But bear in mind that not all homophobia is motivated by Judeo-Christian prejudice. Muslims would be far harsher, for instance. And bigotry even exists among non-believers. Homophobia is prevalent across many societies, and is often not linked to religious beliefs at all.