@ Jeff -
Dude, don't be so impressionable. f**k these people! In the most intimate and caring and gentle way possible of course, 'cos I love and respect them oodles lol

. But we're just clumps of text on the internet. Don't beat up on yourself because of anything you read here. You've got plenty of reason to keep your godless heathen ways on the D.L. in my book.
s**t, what better reason do you need than to A.)Keep your financial situation above water B.)Maintain a little peace with the parents and C.)Keep LOVE around???
Unless you're the type cat who's constantly feeling repressed by not broadcasting your atheism to anyone in earshot, or unless you're surrounded by Fundies day in and day out making you sing and dance for Zombie Jesus against your will, what's the rush in unloading 6 chambers of godless on the people who care about you?
Seriously. Unless you feel so put-upon to "come out" that it's making a constant negative impact on your life, who cares? Is it "the principle of the thing"? If so, there are plenty of other atheists out there speaking out against religion who can do so without fucking their lives up flatter then hammered s**t, and I think it's okay to let them handle it if you don't have the same luxury. And there's certainly nothing stopping you from "coming out" to the billions of people on Earth who *aren't* such important parts of your life, you know.
Of course you naturally want to be able to "be yourself" around the people you care about. Maybe you even really feel passionate about "enlightening" them to the Truths you've discovered, or maybe you hate the idea of them being taken in by the scam.
That's all very understandable. But you need to stop, and realistically assess the chances of YOUR position making any difference at all in what they believe or WANT to believe, and wrap your head around the fact that if you can't personally save them from their own ignorance, it's not your fault, it's not the end of the world, and you don't need to destroy perfectly loving relationships for the sake of an unwinnable war.
If you just can't live with yourself being non-confrontational with your loved ones on this one subject, that sucks, but there ARE ways to deal with these situations that are more elegant and graceful then others. Take your time with it, for one thing. Nobody's going to respond well if you just up and say one day "Oh, figgidy-f**k your baby-killing monster of a god." or something similar. At least not people that care about you. They're going to feel personally hurt by it, like a betrayal of sorts, and that's not good for anybody.
With your girl, just avoid the subject altogether as often as possible. I assume she's close to your age - so give her a little time to ripen on the vine. No offense, but you're both still pretty young, and a lot of girls her age still operate on a primarily emotional basis when it comes to relationships... Plus she probably hasn't done much critical thinking on the subject at this point in her life.
But if you're with her long enough for you both to mature a bit, long enough for her to grow a little intellectually and maybe learn a little more about the way the world as we know it actually works (perhaps gently guided to good secular material by you loving and molest-y hands)there will come a time when you can have civil, adult conversations about your differing beliefs and it won't send her immediately screaming for the hills with those deeply-ingrained superstituous knee-jerk reactions.
Assuming she matures, of course. Some ladies will always let their emotional instincts dominate the state of their relationships no matter what, and other ladies will simply never care to learn anything substantial about the world they live in. If that's the case, reaching a point of mutual understanding will take much longer if it happens at all. If she's a serious god-squader, and your atheism means that much to you, and all the stars are mis-aligned and against you, well, s**t. You'll have a whole mess of problems on your hands that will probably end your relationship permaturely anyway.
That's my advice, at any rate, at least when it comes to the girl. Just keep it low-key and take it a day at a time. She'll come around as long as she never has to feel like she has to choose you or her god. Don't give her that ultimatum and you should be fine.
As for your parents... Hell dude. They're your parents. It's not like you're around them 24/7 anymore, so it's not that hard to just avoid the subject if you want, and it's not like they're likely to be swayed by their child's worldview no matter WHAT it is... Assuming they're anything like most parents of course. You're the KID. And you always will be to them.
I gotta be honest, this whole Noble Atheist Warrior ideal of "coming out" for the sake of it, to anyone and everyone who will listen, and hang the consequences, is quite silly to me. I mean firstly, it's a mighty big assumption that anyone gives a flying f**k what your belief or lack of belief is one way or the other. At the risk of damage to the ego, most people just aren't going to care... Unless you're a celebrity or something.
For us normal folks, blasting complete strangers with atheist rhetoric unsolicited, just to make your "voice" heard or "be counted", is exactly the kind of thing that gets atheists a reputation for being "preachy" or "overbaring". You don't need to say "I DON'T BELIEVE IN YOUR STUPID GOD!" and launch into a tirade every time somebody says "God Bless You" after you sneeze, for example.
People are much more likely to focus on the fact that you came off like an a**hole than whether or not you were right or wrong in your one-man arguement. They won't walk away from you going "Wow, that guy had some good points!" or "Golly-gee, he sure made me feel silly!"
They're going to walk away going "Wow. What a loud-mouthed dick that guy was! Like I wanted his fucking opinion!? Who asked!? f**k him!" You'll actually do damage to "the cause" at that point.
You might WANT to go off on every utterance of theological idiocy, sure! I know *I* certainly do! But you gotta pick your battles. You need to determine if it's going to have anything resembling a positive effect instead of just doing it instinctively or because you think it might feel good. To be effective, we need bunker-busting surgical strikes, or a good game of nuclear wack-a-mole, not blindfolded carpet-bombing runs .
2nd, we're talking about keeping a *LACK* of belief to yourself here, aren't we? Not a belief! It's really a response to what other people are doing and saying, not a statement! And you're not the only one out there who doesn't believe. So I say hell yes, pick your battles! Don't just open your mouth and start killing people's gods simply because you feel some sort of existential obligation or duty to. You're not the Great Atheist Hope.
When I say pick your battles, I don't just mean you should put thought into when and where you decide to engage somebody on the subject... If you can, you want to be able to choose the battlefield as well. And the weather. And the level of engagement. ESPECIALLY with people who are close to you. When your girl says "Oh, god was working to bring us together yay!", you don't need to go s**t in her hat and say "I don't believe you, and I think you're wrong in imagining that." if you care about her.
Just say "Wow, that's a really nice thought." Or say "I don't know about god, but I'm thrilled to have you in my life even if it was fish-flavored cheese that brought us together, my little Lamby-toes." if you really feel the need to make your viewpoint known. She'll get the point provided she ain't thick as a brick, and more than likely *SHE* will bring up the subject voluntarily if you can manage to be appopriately unaffected or ambivilent to her magical musings, because she'll be itching to know how you can be so cool about it.
Look, I'm all for being vocal, for outing the retardation of superstitious belief whenever possible, for people standing up and not being afraid or ashamed to say "I DON'T BELIEVE YOU." But you only get so many people in life to care about you, to care for you, to love you, and if perforating THEIR particular beliefs is going to be hurtful to your relationship, I ask, why the hell would you do it?
What are the possible gains, compared to the possible losses? I understand wanting your loved ones to not be subject to the shittiness of religion, absolutely. And if you think you have a shot of pulling them away from it, sure! Give it a shot! But if you KNOW in advance that it's not going to make ANYTHING better, and in fact will likely make things worse or much worse, I think you'd have to be either insanely self-rightous or unbelievably masochistic to damage an otherwise good relationship for the sake of getting something so ultimately useless "out in the open".
"The Cause" just doesn't need lil' ol' you THAT badly, that you need to be self-destructive or be a martyr for it, or even shoulder GUILT of all things for not doing so. There are plenty of atheists out there to carry the torch, and more every day, and like I said, in 99% of our dealings with religious people, we're ALL free to take a stand wherever and however we like. But see, you're not alone in this, and you don't have to single handedly bring logic and reason to the Jesus-ly masses AT ANY COST. That 1% of religiosity you might choose to tolerate in order to better your life will certainly be covered by all the rest of us doing our thing, since our 99% is almost guaranteed to include your 1%.
Youngblood, at the end of the day, you gotta live your life for you and the people you care about, and be happy with it first and foremost, otherwise what the f**k's the point?