Christianity, a religion based on the teachings of Jesus Christ, has about two billion followers. Learn about the story of Jesus Christ, where the Christian faith originated, and how it grew to become the largest religion on the planet.

Grim is knocked away to Holland by Billy and is confused with a prophetic nun after his robe is altered by a series of accidents. He is taken into the nunnery where the nuns reveal that they believe him to be "Sister Big Mama" who happens to resemble him.

John Green discusses early Islamic history and some of the beliefs of followers of the religion. Like Christianity and Judaism, Islam is a monotheistic religion and has religious texts, most notably the Quran. John some of the themes of the religion: strict monotheism and the importance in taking care of others that are less fortunate. Also, he covers the Five Pillars of Islam: Shahada, Salat, Sawm, Zakat, and Hajj.

John Green explains the history of Buddhism and how Siddhartha Guatama, or Buddha, set the foundation for the religion. He briefly discusses Siddhartha's life as a prince and how he became Buddha. John then describes the Four Noble Truths, the essence of Buddha's teachings, and gives a glimpse into the life of monks following the religion. He touches upon how the religion spread and was particularly attractive to low-caste Hindus.

Bilal is chosen to give the first call to prayer during the early days of Islam in Medina.