I consider myself atheist in terms of God being an omniscient, conscious, sentient entity.
The Bible and many other religious texts state God as being perfect. Yet God though of Lucifer as his favorite. In my mind, if one was perfect, one wouldn't have preferences and that affects ones actions.
Also, I really don't like the concept of 'just believe' as I see that as merely bowing down to someone and not thinking for yourself. It makes you a lamb and the one in charge (whether Pope, priest, or Rabbi) the Shepard.
On top of that, every major religion states that if you don't believe in their deity, you are eternally punished.
I don't care what you've done, nothing equals eternity. To me these are not the acts of our 'lord and savior' but the acts of a tyrant.