Again, a gross misunderstanding.
Atheism does not imply a lack of belief (or a belief in nothing (which is a contradiction BTW..)). Moreover, as far as rules go, atheists are more stringent on rule structure than any theist could ever hope to be: you see, we have actual derived rules; ones that are logically sound, and based upon more solid foundations than myth. As for morals, the situation is similar: we have established an effective codification of behaviour, known as Law. Again, supported of course logically, as opposed to mythologically.