I think the holy verses are to provide moral or mental strength as human beings are guided by emotions. Some poets wrote motivational sher for instance Dr. Allama Muhammad Iqbal wrote “khudi ko kar buland itna ke har taqdir se pahle, khuda bande se khud poochhe bata teri raza kya hai” Dr. Rahat Indori wrote " bahut naaz hai dariya ko apne hone par, jo meri pyaas se uljhe toh dhazziya udd jayein". So I think holy verses do the same thing. Again this is what I think and not based on any data and fact or any scientific analysis.