Actually, I will never beleive that. I KNOW the truth...100% positive and sure. I can prove it with my life, how blessed I have been, and how God has worked it in
Here's a funny thing. Before I decided that christianity was not the right path for me, I was wracked with nothing but fear that I would do something wrong somehow and end up being sent to hell. I remember being 5 years old and crying myself to sleep as I prayed. I was stressed, and angry all the time.
Every since going down my own spiritual path, my life has been blessed. I have a good career, my relationship with many relatives has improved, I find joy and beauty in my life. I am with a man who loves me and whom I love.
This proves to me, 100%, that a good life full of blessings is not dependent upon the Christian God. And in fact is sometimes better without. Indeed, I have had it 100% proven to me that what brings blessings to a life is following the correct path for that *individual*, be it christianity, judaism, islam, hinduism, jainism, paganism, or atheism. All are valid paths.
Besides, I've always hated circular logic. "The bible is right because it says it's right!"... but so does Hinduism and Shinto, both of which are far older. No religion is going to say "Follow this one... It's WRONG!"... So all you have to go on is the unsupportable promise.
Thus, agnosticism for me. "There might be something. Might not. If there's an after life, I have a pleasant surprise. If not, oh well."