Sometimes fundamentalist religious people will say that atheists lack a moral and ethical code, simply because they do not believe in a GOD.
Why is that?
After all, most people (with the exception of masochists and the insecure) "choose" their religious affiliation based on their already existing beliefs - or they have their religious beliefs indoctrinated into them by others from an early age, and simply don't have the mental capacity to choose another course. Although, some people do manage to self-actualize themselves out of enslavement to dogma and become free thinkers.
So if you already believe in being moral and ethical, as most people do, what difference does it make what religion you choose?
When did anyone ever say that not believing in a mythical deity was immoral or unethical?
Most atheists choose atheism because they see the intolerance and cruelty inherent in most of the other religions, which are actually far less moral and ethical.
It is safe to say that there are cruel, immoral, and unethical people in every religion as well as atheism. A former boss of mine affiliated himself loosely with Judaism, but was cruel and heartless when it came to using innocent small furry animals in scientific experiments.
There are examples everywhere of religion being used to repress others, even kill them. So to say atheism causes immoral and unethical behavior is a non-issue.