I’ll start with my conclusion: The definition of atheism has changed, in a way most atheists accept. It used to mean “100 percent certainty that there are no gods." Now, for many self-defined atheists, it means “a reasonable certainty that there are no gods." If you don’t object to that shift in meaning, it makes no sense to oppose other shifts purely because you think the word should mean what it always meant.
So what does atheism mean? And who gets to decide?