I was brought up by Christians, in a small town, I was the eldest child. My parents were young and Christian. I grew up with vague fears of the evils my parents saw everywhere they looked - demons, Satanic influence, the occult and New Age.
I wasn't allowed to watch the Dungeons & Dragons cartoon, the Care Bears (white magic!), and I was only allowed to purchase Autobot transformers (Decepticons sounded too much like "deception"). An ironic side effect of this was that my games with my toys always resulted in some of the Autobots turning evil. And I wasn't allowed to watch Scooby Doo.
Somehow, despite my parents' Christian vigillance, I stumbled across the Dragonlance Chronicles when I was young, and also fell in with role-playing nerd crowds. My parents were suitably horrified, certain as they were that people who played D&D ended up worshipping Satan, dressing up and fighting with swords, and killing themselves. (Just ask Jack Chick!)
And then I played Magic: the Gathering when I was 15. That was 8 years ago. Man. Seems like only yesterday. Oh, how I loved my Vesuvan (sp?) Doppleganger. Yea! How I enjoyed using Sleight of Mind. And yet I retained a kind of aversion to cards like Demonic Attorney and Lord of the Pit (putting me at a distinct disadvantage with my five-colour deck).
Wait. What was my point again?
Oh yeah. This Chicken Licken style of seeing "demons" and "demonic influence" everywhere is a tricky little thing. It convinces you that something can make you evil without you realising it, and tells you that by their very nature you won't notice what's being done to you. Then you think, "I'm not noticing anything right now... MAYBE IT'S HAPPENING." And all that.
Magic: the Gathering is a game. You place cards. They have pictures. There are rules. You try to reduce your opponent's score zero. That's it. If you think looking at or reading things that occasionally depict demons can turn you evil, quit reading the Bible.
Nothing's out to get you. Especially not something that "is so derned tricksy that it's liable to say 'nothing's out to get you' just to make sure you're not ready for when it gets you."