In my (admittedly not immense) experience, intelligent theists who commit to rationality (and stay theists indefinitely) either engage in some heavy-duty partitioning of their beliefs - that is, they commit only partially to rationality, and consider part of their belief network exempt - or cover the gaps in their communicable rationality with incommunicable religious experience. In the first case, it's a clear case of not being wholly rational; if we can talk about those people as a convenient, accessible example of not-wholly-rational individuals with an obvious area of non-rationality, and happen not to severely offend anyone here, there seems no harm.

The latter case, however, makes me nervous, perhaps because I have a lot of Mormon friends and they seem to have a lot of incommunicable religious experiences as a group. From talking to my smart, generally rational Mormon friends - at least those of them who will let me interrogate them about this sort of thing - I find that they act and speak exactly like they're applying rational principles to experiences that they have had, which I just have not happened to have.

Since theists include both the partitioners and the experiencers (and probably some overlap and some categories I haven't thought of or met), perhaps we should stop talking about theists in general as our target group and start speaking of some narrower collection of people, if we want to stay with the example of religion for whatever reason. "Fundamentalists", perhaps - anyone who has met an intelligent, rational, non-partitioning fundamentalist will surprise me, but is of course welcome to shoot down this suggestion.