We want some bedrock certainty that our way is the right one. But immediately we discover that believers in every kind of religion and ideology are also nourished by writings which encourage their faith. In India for example the Vedas, Upanishads, and Bhagavadgita are used by millions of Hindus. Muslims revere the Qur'an. Sikhs have their Grantsahib.
Christians read the Bible in their services.
Christian Science needs Mary Baker Eddy's Science and Health , 1875. Jains, Parsis, and Buddhists each have their own writings. And for members of the Communist Party the writings of Marx and Lenin had their special authority. In each case these scriptures use a selection of metaphors and extended metaphors in the form of parables. There may also be some historical or mythical accounts of a people, proverbs, sayings, rules for rituals, laws, morals, and some logical connections between these.