Agree with Riven.
Belief in G-d or not is a belief - you cannot prove or disprove scientifically the existence of G-d.
Your choice to be an atheist affects your daily life, likewise choosing to believe in G-d and having a particular faith affects your daily life, be it what you say, how you say it, what you do with your time, what you eat etc. etc.
I'm sorry to say this, but the most inflexibale and, for wont of a better word, fundamentalist (in relation to their belief) individuals I have encountered are atheists.
I agree that religion is a personal thing and should not be inflicted on others. The other evening, I had some man twat spending most of my train journey about how I should read a book about a Muslim who converted to christianity as it was so wonderful, and blah blah blah, Jesus is so wonderful. I could do without that TBH, and thought it incredibly rude that here's this person, who knows nothing about me, my background, what I've thought about, what I've been through, telling me to believe in something that I categorically do not believe in, and with good reason. I should have twatted him.