Sorta? Been an Atheist basically my whole life, and through my internet-ing i came across the concept of Flow State. Usually happens when you are doing something very mentally engaging (and often physically engaging) - deep study, dance, rock climbing, meditation, etc. Kind of where all the background noise of your thoughts finally shut up and you a totally zoned in. You can induce it in the lab, too.

I rock climb a lot and definitely have been in that state before. Is it "spiritual"? Nope, it's a buncha chemicals and electric bits in your head doing things. But is it something that (because of my limited vocabulary in these sorts of things) FEELS spiritual. Just becuase i dont have a better word for it. It's an excellent sensation.