I'm not sure I agree. I think you're conflating religion with the broader term of spirituality, which indeed is not explicitly rejected by atheism. Religion as in theism / deism, however, is.

It’s not a matter of opinion, fortunately it’s a regular word in the English language that has an established meeting.

First definition I find of religion: "A set of beliefs concerning the cause, nature, and purpose of the universe, especially when considered as the creation of a superhuman agency or agencies, usually involving devotional and ritual observances, and often containing a moral code governing the conduct of human affairs."

Almost every atheist will reject religion, given what religion typically is and which is captured pretty well in the definition above.

We’re not debating the definition of the term religion, but take a look at the definition for atheism. That’s what we’ve been discussing, what does it mean to be atheist?

Believing in god(s) and believing in religion is the same thing, is it not?

Nope. Religion is thinking you can SPECIFY god, and interpret it. Godel had some thoughts about that ;)