The theory or belief that God does not exist. Credit Google. lol. This is hilarious. My point proven. You are wrong, all three of you.
You are now changing the meaning of the word 'belief'.
You could reasonably argue that anything anyone thinks about anything is a belief. I believe this spoon is a beautiful woman. I believe that pigeon on the roof is Englebert Humperdinck.
You have changed the debate from that of theism vs atheism to that of pedants arguing about the true meaning of words.
Do I believe that Man Utd are the best team in the world, or do I just think this? Or is it just my opinion? What about the guy who disagrees with me, is it his 'belief' that Man Utd are not the best team in the world?
You thought you were being clever but you've just shown yourself up. You've been exposed and YOU DID IT TO YOURSELF.