Religion

Everyone derives their morality from somewhere. Some derive it from reason, and some derive it from stone age doctrine that still provides instructions on how to sell your children into slavery and the proper way to beat your wife.

Anyone can be an anarchist by believing any system of control should be dismantled if it doesn't continuously justify itself. Not a bad idea really.

The idea that atheists aren't, or can't be truly moral is just claptrap promoted by religionists who need a system of control not bound by critical thinking. There's no shortage of religionists who most certainly feel no constraint by any rule of law other than the one that was faxed by the almighty and even then only a very narrowminded interpretation. Some of them are even members of the US Congress and every state house has them. They were put there by other narrowminded people who feel the same way.