*Slight spoiler warning*
First of all for the Christian parents 1 star bombing this film: this film it's PG-13, of course it's not for kids! also the director is not trying to make Satan "Cool and kids should turn to Satan Liam (The main character) doesn't go willy nilly with all of his wishes, he was very relucent to use his wishes worrying about what would happen if he used them all (It's kind of hard to make my point without spoiling too much,) and BTW I'm a Christian and got baptized this April so I myself was kind of worried about the Satan symbolism and stuff, but I believe they executed this to make Jack a likable character but not support Satan worship. Yes, if you have underaged kids who'd like to see this film perhaps give it a test screen while they're at school just to see if it's fine to watch.
Sorry about that rant I just got mad with those 1 star bombs. Anyways, I loved the film, and yes it does have some plot holes in the ending, it felt like the super happy fun ending from Wayne's World, and I'd just bet the writers were just trying to give us the most happy ending possible. My favorite part was Jack Black because his jokes throughout the film had me DYING laughing (Not literally though,) although yes some jokes are a little inappropriate that's why the film got rated PG-13.
So in summary don't look at the 1 star reviews because the Christian moms 1 star bombed it, give it a test watch before letting kids under 13 watch it, and the Satanist stuff was managed well. I'd bet this movie will be remembered well for being underrated similar to Rango or something similar to that. And with that hope you all have a Merry Christmas!