Realistically, if none of it exists, it won't matter, will it? :) Think about it: If you die and that's all there is to it, you're hardly going to be aware of it, are you? If death is the ultimate end, you're not going to miss anything because you're not going to be aware of it. I have heard some of the religiously-inclined remark that it's that sort of mindset that says, "Do whatever you like, because there are no consequences." What a load of rubbish. On the contrary, to me it screams, "Make the most of every moment, if this is all there is." If there is nothing beyond, and what we have is all we have, it suddenly becomes a whole lot more precious. If there is anything beyond, so be it - but if there's not, let it be incentive to live, laugh, love and learn as much as you can, and be sure to tell those you love, that you love them. So what if the things you believe turned out to be incorrect? Did you do your best with what you had at your disposal?
"Faith" is belief in the absence of evidence. If you choose to believe something and admit that you have no reason to believe other than you were taught to, or out of a sense of fear or obligation, do you suppose that "God" would respect that? Or do you think that it is more sincere to say, "I don't know" and mean it? Moreover, if you went on having "faith", don't you think that an all-knowing, all-powerful "God" would KNOW that you believed out of fear, obligation, or because you were hedging your bets? To put it in a different light, imagine you're an elderly woman who's amassed considerable wealth during her life. Would you want your children, grandchildren, and so on, to take care of you because they thought you'd reward them with some of that wealth when you finally died? Or would you want their support because they truly loved you? Would you want them to help you because they were afraid of being left homless or hungry if they didn't give you aid, or because they loved you? Likewise, surely an omnipotent deity would know the difference, and if such a being exists, and is fair, then good behaviour from a good heart would be rewarded before obedience from selfishness or fear.
One thing I believe is certain, and that is that no matter who you are or where you are from, you can't go far wrong with kindness. If the things you do, have the right intent behind them, and you don't act out of malice, you'll have lived the best life you possibly can, and even if things do go wrong, you can still know in your heart that you did the best you could. And if there is something beyond, then any just and loving omnipotent entity would know and understand why and how you lived your life, and let's face it, if there is a "God", if s/he isn't just and loving and omnipotent, you're damned if you do and damned if you don't.