Brother, you do not have definitive, clear information on either evolution or the science which claims Neanderthals crossed mated with modern humans. Here's a quote from evolutionary scientists addressing a recent genome study of Neanderthal bones from Croatia: One of the observations made by scientists is that media reporters routinely misrepresent and distort scientific findings to cater to reporters' worldviews and prejudices. The gap between actual scientific findings and media reports are quite enormous and very often the certainty which the media "reports" is not expressed or justifiable from the actual science. Before you start doubting your iman, why don't you read the actual scientific reports? Why don't you read actual scientific findings about evolution. I studied biology in college and much about evolution is NOT contradictary to Islam. Microevolution, such as species adaptation, is compatible with Islam. The major issue of contention is the origin of Man. Evolutionary claims of the origin of man simply lack the certainty to contest the authenticity of the Quran's statements that we are all children of Adam and Adam had no parents. And neither do we clearly understand how Adam was created by Allah from earth or how humanity interbred. The certainty of the Quran remains uncompromised and unchallenged. Neither are scientific reports about Man's origins sufficiently definitive to mount a challenge. Ironically, I've sat among very learned brothers (PhDs in chemistry, MDs, engineers, ulama) who casually pondered how the first generations of Man mated, and whether they mated with nonhumans who lived at that time of the first generations. In terms of possibilities, its possible for the first sons of Adam to have had a Shariah completely unimagined or understood by us, including mating with Neanderthals. Are doubts about the Shariah of the first children of Adam really grounds for doubting Allah's existance, the authenticity of the Quran as established by the arabic, and the prophethood of the Rasul (saaw)? They are not. Rather, doubts which emerge from evolution are based on ignorance about evolution and the Aqidah of Islam as well as falsehoods propagated about both.