Ayn Rand has many things to say about religion. However, I found one of her comments in a place I didn’t expect: the lengthy appendix to Introduction to Objectivist Epistemology (order from Amazon.) Somebody asks her about the conceptual status of “God.” She replies:
[“God”] is not a concept. At best, one could say it is a concept in the sense in which a dramatist uses concepts to create a character. It is an isolation of actual characteristics of man combined with projection of impossible, irrational characteristics which do not arise from reality — such as omnipotence and omniscience.
Besides, God isn’t even supposed to be a concept: he is sui generis, so that nothing relevant to man or the rest of nature is supposed, by the proponents of that viewpoint, to apply to God. A concept has to involve two or more similar concretes, and there is nothing like God. He is supposed to be unique. Therefore, by their own terms of setting up the problem, they have taken God out of the conceptual realm. And quite properly, because he is out of reality. (page 148)
Incidentally, I also found the material between pages 150 and 157 to contain a number of interesting comments about volition and the distinction between mind and matter.