Consider the following analogy:
A young child has an absentee father who has never visited the child and never spoken a single word to him. The absentee father however expects that the child follows all of the father's rules, so he dispatches a friend to relay the message to the child. The friend says "I was sent by your father to tell you how to live; do all of these things". However, the child is also visited by 99 other people also claiming to speak for his father, each carrying dramatically different messages. The child is overwhelmed and doesn't know what to do, so he just manages to live his life the best way he can. Later on, when the absentee father finds out the child didn't do everything he was told, he sends one of his goons to lock the child up in the basement, then torture the child for decades until it dies.
The most fundamentally important reason why I'm an atheist is that I recognize we are presented with an impossible choice. There are hundreds of religions and hundreds of gods in the world, yet there is no objective way to prove one right over the other. For those of you who believe there is only one correct answer, how can any given human being be expected to select the one right religion of the hundreds presented while rejecting all of the others? The vast majority of people in the world never make it out of their parents' religion, so if you believe in eternal hellfire, you believe most people are inherently doomed based solely on where they were born and to whom.
God, like the absentee father, could easily just tell us his will directly and unambiguously, instead he chooses a medium that can be easily falsified and has 100 other similar religions that have contradictory accounts. There is no way to determine which account actually comes from god and which doesn't. A parent doesn't torture their kids for their entire lives when they screw up, they briefly punish the child and guide it in the right direction, so why would god act any differently?
