John Calvinâs Institutes of the Christian Religion is over 1000 pages long. âOf Prayerâ is a manageable excerpt from this monumental work highlighting the theologianâs views on the nature and benefits of prayer. Calvin describes why praying to an omniscient God is still a necessary practice for Christians. He provides some helpful guidelines for prayer, detailing how to invigorate oneâs spiritual life through reverent communication with God.