If you define a religion as a belief system about God, then atheism is a religion.
I was intrigued with a question Dennis Prager said he would ask an atheist acquaintance. posed not as a "trick" question; rather, asked as a legitimate question to assess the person's thoughtful consideration of belief or non-belief in the existence of a Creator.
In paraphrase:
You do not believe in the existence of a Creator -- an afterlife -- and I do so believe. One of us is right and one of us is wrong; that is, we both cannot be right. My question: Do you hope that it is you who is wrong?