C. S. Lewis wrote “I was at this time living, like so many Atheists or Antitheists, in a whirl of contradictions. I maintained that God did not exist. I was also very angry with God for not existing. I was equally angry with Him for creating a world.”
Some atheists have maintained that this shows that Lewis was never a real atheist. However, recent social science suggests that atheists really do get angry with God.
Even those who didn't believe in God were sometimes angry at the deity. College students and bereaved people who were atheist or agnostic reported more anger at God than religious people in the same demographics. The findings don't contradict the participants' agnostic or atheist beliefs, either: The study asked people about past experiences, and many atheists and agnostics had stories of anger dating from their religious pasts. Many of the study questions also asked atheists and agnostics to imagine their feelings toward a hypothetical god.
Full discussion here.