"Atheism" does not rule out higher forms of consciousness. Many people construe it as such, and indeed many "atheists" do subscribe to this, out of a blind rejection of gods and religions (which I will not necessarily call misguided, as surely many of them have good reason to reject such religions and gods, given that it has been used to control us to the degree it has). But many cling to the rejection of anything that isn't naturalistic with the same degree of faith religious followers have. They immediately reject anything that their education, particularly in the sciences, has told them isn't possible, or hasn't found proof of. While many atheists are not like this, a large minority or perhaps majority have retained faith in their beliefs, or disbeliefs.
When I was a child I had a loose belief in God (I never attended church or anything like that, I just believed largely because it was what I was told was real - though it wasn't drilled into me extensively by any stretch of the imagination; it was kind've like Santa Claus and the Easter Bunny). I shook this off when I was 11 or 12, becoming an atheist and then agnostic. Now I know that higher forms of consciousness exist, because I have experienced them; a few of the times through the use of psilocybin mushrooms. This does not make me a theist - I still have no more belief in the Judeo-Christian God, Allah, the Hindu ones, Greek, Roman, etc. than I do in trans-dimensional leprechauns and pixies controlling the universe. The evidence for their reality, to me, just doesn't add up.
I think in absolute atheism, and theism, the problem is faith - in belief without any evidence. It's a disease of the mind that is hard to overcome; it's one that cripples our ability to learn new ideas and come to new understandings, as there are certain beliefs we won't question. Few people are willing to admit with many things, that we really don't know what the truth is. I'm comfortable with the fact that I don't know everything; but I'll certainly be learning as much as I can while I'm here.