Suppose you had brain damage and a doctor prescribed some tongue-twisters for you to recite in order to exercise specific parts of your brain. Would you object based on the semantic content of the tongue-twisters? If one of the tongue-twisters was "Our father who art in heaven, hallowed be thy name", would you object to reciting it because you disagree with what it means? What if clinical trials had found that particular phrase to cause the necessary brain exercise, and no-one had discovered any alternative ways to achieve the same exercise?