Ok, that sounds good. Thanks for the discussion so far. But real quick, may I ask you this question: What is the inverse of the statement "I don't believe in God?" Seems there should be an inversely logical conclusion. "I don't believe in God; therefore, inversely, I do believe there is no god." I don't believe x; therefore, I believe in the opposite of x. It sounds like a mathematical equation because it is.
It should be obvious to everyone with a functional brain that "I don't believe you killed Mrs. Jones" is not equivalent to "I believe you didn't kill Mrs. Jones" when both evidence and alibi are lacking. If criminal investigators and courts applied this kind of logic, criminals would be set free and innocents would end up in jail at the toss of a coin. And worse - we wouldn't have detective novels.
The choice here is ternary rather than binary: lacking evidence for either possibility, "I don't believe either" is always a reasonable alternative.
Your friend needs to take a refresher course in logic. This is called a false dichotomy, because "I don't believe in God" and "I believe there is no god" (what's with the first assertion having a capitalized word "God", which "God"?) are two entirely distinct claims. He's decided arbitrarily that something is "the opposite" of something else, and decided that those are the only two options. (And I consulted with my son who is taken a course in formal logic as we speak).
What if there are many opposites?
I don't believe X doesn't tell you if I believe Y, A or Z.
It just means I don't believe X.