Camarath said:
I can not find a rule that prevents clerics from using their spell casting ability if their Intelligence score is 1. You can read such a provision into the rules if you want to but I don't think it is there.
Intelligence is the essence of quick thinking, witty comebacks, and leaps of logic. Wisdom is the ability to slowly figure things out, and come to an understanding of your surroundings that otherwise might be left out. Raistlin and Caramon from Dragonlance are prime examples. Raist always had the quick answer, due to his high intelligence. Caramon was often thought of as stupid, yet his wisdom was actually quite high, giving him the ability to reason out quite insightful answers to problems, given time.
With an intelligence of 1, a character cannot speak a language, and must communicate through other means. I can't find it in a quick skim of the 3.5e players, but I do recall it in my 3.0 players, though I don't have that with me to check. Therefore, without the ability to speak a structured language (such as the arcane phrases and divine prayers required for spellcasting), any spells with Verbal components are now unable to be cast. However, a cleric could still theoretically cast a spell without verbal components. The problem is now - without the intelligence to quickly reason out the best choice for the given situation, what spell would they select, and how appropriate would it be?
Theoretically, a cleric should have quite the fearsome wisdom, so they may actually hit the head of the nail dead on, and come up with the perfect spell to cast in the given situation. Now, the tough part. How long does it take them to intuitively figure this out, without the reasoning power to go along with the wisdom? Personally, I'd say they'd likely be thinking for most of the entire combat, if not all of it, on what spell to use.
Outside of combat, however... perhaps they may be able to come up with a way to reverse their condition... in a few days.
