- Doctors Of The Church: Thirty-Three Men and Women Who Shaped Christianity
- Antichrist: Two thousand years of the human fascination with evil
- Christian Spirituality I: Origins to the Twelfth Century (World Spirituality: An Encyclopedic History of the Religious Quest, Volume 16)
- The Foundations of Mysticism
- Early Christian Mystics: The Divine Vision of the Spirtual Masters