Honestly, the "concerns about grooming kids" schtick has never convinced me (as someone who was raised in a shitty ultra-religious family myself).

The simple truth is that "love the sinner, hate the sin" never actually works that way. For most bigoted types, there's an inherent hatred already there in fact (founded on insecurities, whether it be of their own sexuality/masculinity/femininity/etc, of the sort where they can't handle people not living according to their rules and beliefs and it hurts their ego, etc). Anything afterwards is just an excuse, not that they need one, but they'll certainly use it.

Directing hatred at some distant group also is- its own kind of catharsis? It may be unhealthy, but I suspect it's pretty common. Personally (as someone who's trans and queer AF)- as a kid, before I knew or was comfortable with myself, I used to be (and was raised to be) homophobic myself (though I wouldn't have been nasty to someone if I knew they were gay) and can even remember talking in jr. high about wanting to "kill racists and gays" (to which my teacher had the decency to ask me what gay people had ever done to me- and I walked back on that one. Anyways I was a troubled kid as an understatement).

In my own experience, it was in some considerable part insecurity- but added to that, I wanted an outlet for my anger and bitterness, I suppose. What I'm talking about is over a decade ago at this point (I'm in my late 20s) and I'd like to think I've become a much better person since (and can recognize that- on some level, kid me didn't have much of a chance if any of learning prior).