An athiest can be a JW, and it is hell. I was an athiest-JW for about 7 years before I left, and a Ministerial Servant to boot. I was giving regular public talks and parts on conventions. I was regular in service and auxillary pioneered often. It was terrible. At times it would make me physically ill. I was doing it for falmily, but came to the realization that I couldn't keep doing it.
I would say, though, that I had just as much holy spirit as the others did - none.