Where are you from? That sounds kinda extreme, in my country, beliving 100% in God is considered odd, though no one would bully you for it.

Me again, lol. A question I has. Why'd they ask you if you believed in God anyway? It's a yes or no question, if not a complicated 'gray' one. Either way, if you don't answer 'yes' with nothing else attached to that, it should suffice to say that...you either don't believe in God or it's complicated. Not that hard to figure out. But they chew you out for it anyway. I'm thinkin'...they premeditated chewing you out. "Okay, if they don't answer yes, we're going to chew them out." Otherwise, what's the...point of...asking....if it's not to satisfy some sort of curiosity? If they expect ahead of time that you're going to answer 'no', which is what you NEED to do in the event of asking a yes or no question, is it really even necessary to ask? Why couldn't they just go, "What's your belief system?" instead? It's way more polite and easy and they wouldn't have ended up looking like total idiots in the process.

Find new friends.

There is nothing you can do.
Most likely the kids who are tormenting you are not tormenting you as a direct result of your belief system, but rather because they are miserable.
When you are miserable, you need someone to be more miserable than yourself to make you feel better.
They don't really care about your religion, they only care about you as a target for all their own suffering.

Normally people would say to "just ignore it" but silence/ignoring is a response within itself.
The only way to get rid of this kind of treatment is to be extremely happy and positive.
Your responses to any teasing should somehow be optimistic and bright.
Straight back, smile big.

If someone were to walk up to you and say,
"You're a satanist, aren't you?"
Say something happy back like,
"I'm not sure who's a satanist, but it's not me~ Hey, does the weather seem weird or is it just me?"
Change the subject if you can.

If you keep this up, then the bullying will probably fade away.
Never say you're a satanist, even sarcastically.
Never get mad.
That's all the advice that I can give.

Unfortunately bullying, opression and generally bullshittery is a very common thing when it comes to atheists. Hell I've had teachers bully me and harass me. One even told me that I was "autistic because I didn't believe in Jesus." and tried to send me to get tested by a doctor. -without telling my parents- (plus my family has no history with autism or aspergers ect.)

I had an incident like this at work a while back. I'm not an Atheist...but I didn't follow the same religion as the person who confronted me. Mind you, they confronted me like this...in the line. I work at a department store...and here I am, trying to check people out and keep the line moving so nobody get's angry and stuff. You know. Customer service and what not. But lo and behold....this elderly fellow comes to my register to check out and instead of showing me his driver's license, which I needed in order to make sure the info on his check was right (otherwise, I can't scan it), he shows me his membership card to...some church in the area. And then he kind of grins and boasts about it. Like, "That might be my driver's license, with my address and picture on it and everything....but this is really who I am. What I'm a part of." That's not what made things awkward, though. Hell no. I thought he looked way too smug while I was trying to be as serious as possible about this driver's license business, but hey. Nothing wrong in feeling proud about your belief system. What made me flustered was that he asked me what church I belonged to, kinda just...assuming I went to one at all. I told him honestly that I didn't go to church, nor was I a part of one. That my 'religion' was more of a philosophy than anything else.
He looked curious as first...asked me what it was, of course, so I answered 'Deism', because it's the closest thing I actually feel associated with. I kinda grinned myself. Feeling my own surge of....national pride as I shortly stated that America was founded mostly on Deistic views and that most of the founding fathers were in fact Deists themselves. I thought it was a neat little...piece of information for him to have since he was living in this country after all and...not many people know that in my neck of the woods. I'm also a history nerd. I'll spout random bits of...historical trivia at random times.

"Well then...what do you do about Jesus?" is what he asks me next. Meanwhile, there's a lot of people in line....and it's sure not flowing....I'm starting to get nervous. Not just about that, but about being put on the spot as well. I really didn't know how to answer that question.

I just kind of looked at him like, "....He......exists????????....He's.....there??????" I didn't know, lol. Jesus isn't a big deal to me. So...in as polite and unoffensive way as I possibly could, I explained that I thought Jesus, if he existed, was an ordinary human like me and him and that...there was really nothing...I could do...about him.

It's at that point that he's not smiling and asking questions anymore, but kind of....glowering at me. Definitely a , "Son, I am disappoint," face. Fortunately he eventually did leave and go on his merry way, but the sense of awkwardness I felt after that conversation didn't leave until closing time. Was it really necessary? I mean...there's a time and a place to talk about these things, you know? And in the middle of your shift...at work....with people everywhere.....is not the place! So after I gave him all that very personal information for not only him, but everyone else to hear, I kept having the feeling that the other customers were judging me as well. That I was going to get ANOTHER person at my register...glaring at me like, "You non-believer, you.....Just ring up my shit so I can get the fuck outta here."

Needless to say, I learned my lesson about revealing my actual 'religion' to total and complete strangers. >.<;;; Next time I'm just going to lie and...make up a Christian sounding church name, lmao. I feel that if I say something like, "I really don't want to say, it's kind of personal," that the questioning stranger will hammer me with questions I feel uncomfortable asking, therefore making the conversation that much more awkward.

Just don't say anything at all. Don't even open your mouth or look at them. Just sit, draw, read a book or something. They might get bored of pestering you. Don't give them something more to argue about.

Some kids just want a reaction out of other people, it's fun to them.

When I was in elementry school, it was hard for kids to bully me because I never said anything and just ignored people attempting to get me down.