The main topic which led me to question Islam was evolution. There is so much evidence that supports evolution from genetic information and the dissemination of protein. ... All life on earth is related that is to say that all life is derived from a common ancestor. From your own unbiased critical thinking skills would you say that Cats and lions are related? Analyse their genetic information, their phenotypic appearance and even behaviour, there is no doubt that they are not. Comparing that, the Quran stipulates that all humans descend from Adam and Eve. Did God give the bonobo chimpanzees the very striking appearance of that of humans or do we share a common ancestor. This was one topic that I was pondering on for a very long time.
Another topic was the supposed scientific miracles of the quran, all the "miracles" that were presented such as the embryological one and the big bang theory was already in existence in the form of literature. This was known knowledge. People weren't as bereft of knowledge that we like to assume.
There are so many reasons that prove the quran to not be true. There are a lot scientific inaccuracies. Please note that I am not an atheist, Im actually a pantheist.