Well, that assumption is often the case... however, like I said I know that some believe in eternal matter. It didn't have a cause it just always was... and it eventually formed the universe or whatever. Either way it's no cause... or caused by something that was always there and therefore... had no cause.

Those are the only athiest explainations that have ever been explained to me. If you have another one I'd be interested in hearing it. Pm if you like. I really am interested in all views on that subject.