A lady enquired whether some superstitions might not be good for ignorant people, who, if they were without them might perhaps be without beliefs of any kind? ‘Abdu’l-Bahá replied that superstitions were of two kinds; those that were harmful and dangerous, and those that were harmless and produced certain good effects. For example, there were some poor people who believed that misfortunes and punishments were caused by a Great Angel with a sword in his hand, who struck down those who stole, and committed murder and crimes. They thought the flashes of lightning were the weapons of this angel, and that if they did wrong they would be struck by lightning. This belief caused them to refrain from evil actions.
(‘Abdu’l-Bahá, ‘Abdu’l-Bahá in London, p. 73)