This is a fallacy in supposition. It is the same as asking if there is a largest natural number. First of all, God is not a part of the set we call "reality". Reality where God is part of it means either God is limited by that reality or that reality has no limitations, both of them going against our definitions of "God" and "reality". Let's say you have a folder on your computer holding all the folders, and I mean ALL the folders not ALL THE OTHER folders. But does it? Shouldn't that folder be included in it self? It is clear that "root" folder is NOT containing ALL the folders as it does not contain itself, thus we introduce category "Drive", containing "Folders" on the drive but not itself. Differences between a "Drive" and a "Folder" are pretty obvious, as one is pretty much based on reality, call it hardware, and the other one is a construct, thus you have God to be based in reality and everything else to be a construct . The equivalent of your question is: can we have a folder on a drive that cannot be read? Yes, and as unreadable part it is discarded from the drive partition table.

So the answer is yes, there could be a rock that cannot be lifted, but that rock cannot be a part of our universe.