There is a huge difference between the modern god of Judaism, Islam and Christianity, and the old gods of the Ancient Greek and Roman ideologies. In the ancient religions, gods were known to have pretty tangible personalities. There was this idea that the Greeks made gods out of their heroes, and humans out of their gods. In sculptures, men like Hercules are depicted standing strong and proud, but when it comes to the goddess Nike, they show her trying to fix her shoe, so human that she has trouble keeping her laces tied.
This was because the ancient peoples believed that gods were vengeful. They could be cruel, selfish, and vain. They could be competitive, leading to the wars, earthquakes, and plagues. In the modern idea of god, especially in the three aforementioned religions, god is kind, all-knowing, and all-loving (although admittedly with some elements of heavy wrath in the early days).
Atheists and agnostics then have a question. If god is kind, why is there sickness? Why do things like eye-worms exist? Why are there hurricanes and earthquakes? It is easy to understand why when there is a vain goddess like Aphrodite, who wants to knock a few women off their pedestals, but when god is kind, it makes less sense. Rob Bell, author of How to be Here: A Guide to Creating a Life Worth Living has a very good point. Atheists have done a lot to move society forward, and one can even think of their refusal to believe as a gift.
Many people have gone to war for their god. People have died over their personal beliefs, and it is quite heartbreaking, to think of every person who has died in the name of god, whichever god that may be. But the common atheist looks at that, looks at all the death, and all the people who have had rights refused to them in the name of religion, and says, ‘No. I think there may be another way. I have too many questions to go with that.’ This ‘no’ speaks to a certain tenderness in their heart, and Rob Bell says that religion listens. Atheists push religion to refine itself and become better, to adapt to modern times.