Being evil is an attribute of Humans, any of them can be one. It is an instinct of some people. Those people can be Muslims, Christians, Jews, Hindu, Buddhists, or whatever. Generalizing an entire set of people based on either their race or religion can never be factually correct.
We have all seen examples of terrible people from all faiths, and we have seen examples of amazing people from all faiths. Following a faith doesn’t change your instinct (usually).
I am a Muslim, I don’t believe atheism is the right way, but I would never generalize them with being evil.