Although Christianity still exists in post-War America, its overall influence has waned. Many new religions have sprung up in its place. Where Christianity still holds sway, it has scattered into even more splinter groups, such as the Catholicism-derived Saint Monica's Church in Rivet City and the Abbey of the Road, a Christian monastery somewhere west of the Commonwealth. Mormonism still exists as well, predominately in the town of New Canaan.
- James and his wife were particularly fond of a passage from Revelation, Chapter 21, Verse 6, from the Christian New Testament: "I am alpha and omega, the beginning and the end, I will give unto him that is athirst of the fountain of the water of life freely."
- Due to the Christian nature of most of Vault 101's residents, including the aforementioned couple, it can be assumed that the Lone Wanderer was raised as a Christian.
- John Cassidy has at least some knowledge of Christianity, noting that the "good book" does not mention the possibility of the Garden of Eden coming in a kit.
- Marcella is a Christian missionary located at Point Lookout.
- Father Clifford and his acolyte Diego of St. Monica's church are notably Christian.
- O'Hanrahan, a Private in the New California Republic Army, was raised a Christian.
- The New Canaan settlement is Mormon, as are Joshua Graham and Daniel.
- Father Donald, a Christian priest of Coldwater.
- The Lone Wanderer is predicted to becomes Vault 101's priest, if his dominant skill is determined to be Barter at the G.O.A.T exam.
- The Yangtze Memorial's cross predated the bombs, and is not an indication of any current Christian influence.
- Dialogue choices throughout Honest Hearts heavily imply that the Courier has never heard of Christianity.
- The Courier may obtain a copy of Scripture, the holy book of Christianity, after completing Honest Hearts.