Did one study Quran from cover to cover, please.
There is no need to study the Quran once it is realized that it is based on belief in a supernatural god being similar to Christianity and other religions. And no such beings have ever been shown to exist in any form. This alone is sufficient reason to classify the Quran the same as the Christian bible and other similar holy books, and reject them as simple myth and allegory written by scientifically illiterate people living in different times.
Children generally adopt the religion of their parents and local society and mostly stick with it for the rest of their lives. It is hard to get many people to step back and look objectively at their religion, and draw conclusions based on a rational analysis of their history, the origin of the various stories involved, etc. They just blindly believe and never question, and willfully remain ignorant of other ideas and viewpoints.
So I'd argue that religion is borne more of ignorance than atheism. The refusal of a huge number of people to even look at the big picture and do their own analysis almost guarantees this.