Image from Village Zendo.
There are the official, canonical documents of the world religions, of course. The stories and even the writing style of the Bible has affected western writers for centuries; its power and declamatory style make for very effective fiction writing. In particular, I can see a fave writer of mine, John Steinbeck, being strongly influenced by the Bible. Other writers have borrowed cadences or whole passages from the Qur'an, the Torah, the Vedas, the Sutras, and others. What fascination do religious texts hold for writers?
One attraction, I think, is the combination of antiquity and universalism. These texts come from unimaginably distant civilizations in human history. At the same time, the concerns they express are astoundingly similar to the problems we face. These documents ask poignantly what the role of families versus the church is, or how we can overcome the fear of death. They show the tenderness of human relationships, such as the touching tale of Vasitthi the Madwoman in Buddhism. In this tale, a woman's child dies, and she goes mad, refusing to believe that he is dead. She carries his body from door to door in the village, begging for help. Only the Buddha can make her realize both that her son has died, and how inevitable that death was. Her grief is as palpable as it would be today.