On a purely practical level, music is one of religion’s most potent tools. No spiritual convictions are required to see that music touches something deep within us. Take, for example, its mnemonic properties. From “Jesus Loves You” to “Amazing Grace”, music can give theological ideas a special durability and accessibility. This power can be seen outside of religion as well, with things like the alphabet song. Just as Plato and Aristotle noted, music is quite educationally useful. Music can educate spiritually as well as it can practically.
Music can reach people in ways that other forms of expression can’t. One of the most powerful examples of this is its effect on those suffering from dementia or Alzheimer’s. Patients who have lost all communicative faculties, even those who are essentially catatonic, often still have intense responses to music. Patients who never speak will sometimes still sing along with familiar music. Music’s therapeutic properties extend far beyond dementia and its ilk. Music heals the broken heart and the troubled mind. Music’s healing property is an empirical fact. There is a great deal of literature on the efficacy of music therapy.
Religion heals as well. People often find great solace in faith. It provides answers to moral, emotional, and existential questions. Studies of well-being typically show religious people to be generally happier than the non-religious. Because of their healing roles, it’s natural that music and religion would have an affinity for each-other.
If we move beyond secular, naturalistic conceptions of the world, another reason emerges. Music is numinous. To borrow language from Rudolf Otto, music can put us in touch with something “wholly other”. It inspires great and terrible feelings within us. It connects us to the Divine. The goal of many religions it to become closer to the Divine. Whether it is the God of Christianity, or Nirvana in Buddhism, religion so often involves seeking something “other”, something divine. Music is one such connection, and as a result is indispensable to worship.