Here is my argument, arranged point by point:
1) An atheist does not believe in a supernatural force outside of the universe that created moral laws.
2) If nothing made the laws, then the laws cannot exist
3) Therefore an atheist is speaking nonsense when he claims there are objective moral laws
OBJECTION 1: The laws are just there, and even if nobody made them it doesn’t mean they’re not there.
My reply: A moral law is not the same as the concept of thought or triangle. For it to be moral in any meaningful sense, it needs to impose some sort of obligation on me. But if nobody created the laws, nobody is imposing any obligation on me. It is absurd to say that I am obligated to the laws themselves, as they are not sentient. To say that I am obligated to others is also absurd, because that would be a moral law, and this circular.
To put it another way: To say that this moral law I discovered through logical deduction means I’m obligated to follow it still makes no sense, since there’s no reason I’m obligated to follow it.
Therefore, whatever I have discovered can’t be moral laws, and only seems like them to me.
OBJECTION 2: By saying that somebody would owe you an obligation, you are implicitly admitting a moral law, that is, in certain circumstances you would be obligated to do something. So your position is self-defeating.
MY REPLY: Not really. The idea of owing an obligation only makes sense if there’s a lawgiver. That’s my whole point. With no lawgiver, no obligation.
Thus, if an atheist wants to be honest with himself, he has to be a nihilist (of course, he has no obligation to be honest.)
So what’s off about this?