The charitable interpretation is that most people -- even atheists -- will have a belief system that is functionally equivalent to a religion.

> Atheism is to religion as being silent is to speaking – and you're essentially claiming it's just another way of speaking.

Another way of saying it is that religions (as we know them) are answers to questions, you can get rid of those answers, disagree with them, etc. but the questions will remain and you will implicitly provide answers to them. Those answers will constitute what your religion is -- albeit one might not examine their answers in any detail.