From wikihow: How to become an atheist
Step # 5:
Consider your ethics and try to understand where they come from. You don't need a god/gods to be moral. Atheists are not unethical. Like many theists, many atheists donate to charity and live lives that are morally similar to those of theists. Atheists just might have different motivations for doing so.
It's interesting that someone put the thought and consideration into this. I like the well reasoned approach, and it does describe the process I went through starting about 20 years ago.