I'm an atheist because I'd rather believe and live the truth, however uncomfortable, than believe and live a fantasy, however comforting and self-aggrandizing. I value and admire intelligence, and even the smartest person turns into a complete fucking idiot when he starts talking about his religion.
I'm an atheist because I reject slave morality in favor of the morality of freedom. My conscience demands I stand in opposition to any human being whose sole claim to authority and power is the asserted favor of a sadistic, psychopathic and entirely imaginary deity. Even if I'm wrong, and the despotic, sadistic psychopath depicted in the Christian Bible or the Koran were to actually exist, my conscience equally demands I stand in opposition to such an evil being. Better to rule in hell than serve in heaven.
Let me be blunt: if you are a Christian or a Muslim, I hold you in utter and complete contempt. You are nothing but a slave to fear, however you obfuscate and bullshit. You are destroying not only your own life (which is your own to use or waste as you please), but the lives of millions, both the heretics you slaughter (or stand idly by while your brethren slaughter) and the brainwashed masses who never even get a chance to learn to think and feel as free people. There's no more room to be a "moderate" Christian or a moderate Muslim than there is to be a moderate Nazi: you either stand in total and complete opposition or you are complicit. I am an atheist because I am not complicit.
I'm an atheist because I fully and wholeheartedly endorse the slogan that humanity will not be free until the last king is strangled with the entrails of the last priest.
The rest, as they say, is commentary.