giving hit points and an alignment to such evil demons as Garl Glittergold shows a kid how to worship a pagan deity. How so?
Well, you asked:
1) The people scared by this stuff live in a world where God and Satan are omniscient, they pay especial attention to your words and thoughts. So talking about, thinking about, or having art about demons is like saying, "Voldemort." Also remember that all pagan dieties (all good gods in D&D) are masks of Satan just might answer to his name. Better just not to do it, and especially important not to let your kids do it, who might not know what to do when Satan literally shows up to answer some innocent statement a kid said.
2) Many religious rituals, involve talking to spirits who aren't there or re-enacting old events. Christianity talks to God & Jesus, occasionally angels and in most faiths no one pretends to be them, but in pagan (remember to these people this means satanist) religions rituals are almost indistinguishable from live action RPG games. I'd say it's coincidence, but you also have to remember that to a very religious there is no such thing; there are forces of God and forces of the Devil and God only commissioned one book.
3) Violence. Even in the modern, I thought we were done with this kind of BS, age, DnD got blamed for either instilling or showing the violence in the Columbine shooters, and had even my otherwise very progressive mother was a little worried about this aspect.
Of course, the fear mongers go waaay farther than the points I made above into ludicrous territory. "What is the difference between saying 'I cast a fireball' and learning real magic?" Or just completely making up satanist bullshit instead of actuallt looking into what the games are actually about.
Since this is probably the only post I'll make in this thread, let me throw in this real anecdote from my court interpreter stepmom: A prosecutor is telling the court how the defendant has a propensity for violence which you can see because he likes DnD, like the Columbine shooters, and continues to describe the horrible violence in this game. The judge shushes the prosecutor and announces "I know quite a bit about this game, I'm a fifth level elven mage in my gamer group."