Full Title: The Christian in Complete Armour (Volume 1) A Treatise Of the Saints' War against the Devil: Wherein a Discovery is made of that grand Enemy of God and his People, in his Policies, Power, Seat of his Empire, Wickedness, and chief design he hath against the Saints. A Magazine Opened, From whence the Christian is furnished with Spiritual Arms for the Battle, helped on with his Armour, and taught the use of his Weapon: together with the happy issue of the whole War

William Gurnall's The Christian in Complete Armour "is the most well-known of the Puritan manuals on spiritual warfare, and has provided much spiritual comfort for beleaguered saints over the centuries." Joel R. Beeke and Randall J. Pederson in Meet the Puritans: With a Guide to Modern Reprints.