When I became convinced that my belief in God was poorly founded, I worried intensely that I would become a nihilist and/or feel a perpetual vacuum of value. I've been incredibly relieved to find this fear unfounded.

On the nihilism front, I found that even in the absence of any Framework of Objective Value, I still cared about things (the welfare of friends and family, the fate of the world, the truth of my own beliefs, etc). I had thought that I'd cared about these things only insofar as they fit within the old FOV, but it turned out this fear was just a defense mechanism I employed in order to resist changing my worldview. Even with the FOV gone, I am simply the sort of being that cares about these things, and I don't need the permission of anyone or anything to do so!

I feel the same sense of purpose, passion, and meaning about these matters now that I felt when I was religious. Life is at times less comforting in other ways, but my fear of nihilism was misplaced. (Worse, it was subconsciously manufactured in order to stand in for other fears related to leaving religion, so that I wouldn't have believed someone else telling me this until I went through it myself!)