There can't be an ideology of atheism for the same reason there can't be an ideology of theism. You can have an atheistic ideology, which isn't the same thing.
And for what it's worth, Dahmer didn't claim he killed because of atheism, he claimed atheism didn't stop him from killing. Of course it didn't, it's not an ideology, it doesn't justify any action or inaction. Normal people don't need a justification not to murder, because they don't want to murder anybody. Nobody kills in the name of atheism OR theism. Where ideology or religion enters into it, it's a specific ideology or religion, and not a synonym for atheism or theism.
And for what it's worth, Dahmer didn't claim he killed because of atheism, he claimed atheism didn't stop him from killing. Of course it didn't, it's not an ideology, it doesn't justify any action or inaction. Normal people don't need a justification not to murder, because they don't want to murder anybody. Nobody kills in the name of atheism OR theism. Where ideology or religion enters into it, it's a specific ideology or religion, and not a synonym for atheism or theism.
