I'm pretty sure this is how my father would have reacted (and still would react even though I'm at least 10 years older than this kid) if I told him I'm an atheist. Hence, I just don't tell him. It's odd...the kid obviously lied to her & the bishop & whoever else because he wanted to keep it happy, and he probably knew this would be her reaction. And would this mother rather her child keep up the lie than express how he really feels? It's something I still struggle with; do I lie to fit in? Or do I make my beliefs obvious and piss people off?
Granted, the kid may just be rebelling... kids at that age do that... but yelling and threatening church is obviously not the answer (and not the Christian response either.... she needs to re-read her WWJD bracelet and think about what that means).
The part about threatening to take away Chirstmas presents is also hilarious.... ya know, cuz Christmas (with the Santa and the shopping and the electricity-hogging lights everywhere) is all about Jesus.