Here are my reasons why I don't believe in a personal god. Obviously I have been influenced by various thinkers and writers. I am not going to acknowledge them individually.
1. I don't buy the "god created us/universe" argument. While I am interested in the original of universe, putting a god there does not add any value to the quest of the beginning of the universe. It only shifts to "where does the god come from"?
2. The flip side of adding a god in the "beginning of unverse' also adds another difficulty in understand the origin of intelligence. Richard Dawkins/Darwin have provided a great insight - the climb of mountain of improbable. By introducing an intelligent designer, we are dumbing down. By accepting an evolutionary nature selection, add some random variations and with lots of time, I can see a gradual path for intelligence to develop.
3. I am aware of The simulation argument. Can god be the simulation designer? Again, this question is just another variation of (1) above.
4. OK, there may be some intelligence which have evolved before us and hence has arrived to a level of intelligence that they decided to create a simulator - and we are now living inside that simulator. "Ah," the theist may say, "I told you so." But, in this case, the simulation designer is NOT the kind of god theist has been promoting all along. I cannot see any reason why such designer (it) would be interested in every individual human being's moral value. I cannot see any reason why it would demand worship like god. I cannot see any reason why it will alter the rules/laws in the simulator to "answer' some of the prayers.
5. When I was born, I was born without knowledge of my existence - until I have learnt sufficient to start my own independent thinking. When I become old, very old, the neuron connections in my brain will begin to break and malfunction. I will start to lose my accumulated knowledge and my self conscience. When I die, I will not bring away anything except leaving some memories to the people who know me. I believe that when I die, I will just go to sleep, no dream and just will not wake up again. The atoms that are my body will return to where they belong.
6. Judgment Day? No worries. I have been honest, hard working and commit no crime. I have nothing to fear. By the way, this is a good story to read.