Any Christian wanting to advance in appreciating the spiritual land open to them in the power of the Spirit, will find there are many influences to deter them. A warfare is on! The attacks are Satanic. Some are direct, others are subtle. The Christian's strength is only in the Lord Jesus Christ, but He provides armour to meet the attacks and tricks of the devil. Almost the last item in the armour available is "the sword of the Spirit, which is the word of God". It is not our sword, though Christians sometimes refer to their Bibles in that way. The Holy Spirit is the source of it, and the power for right usage of it, whether on the defensive or on the attack. We need skill in its use; we need to let it discern and shape the thoughts and intentions of our own hearts first. Peter, with a sword, was an unskilful user at it: he was more at home with nets! He lashed about with that sword: it was a poor shot! In the Lord's hands the damage done was repairable. We need training in private with the Lord, alone with the Word of God. Then we shall not make wild sweeps with texts of Scripture, but find the skill to use the Word wisely, graciously, and in a way that even the devil will have difficulty in rebutting. In this book the author presents his systematic examination of what the Word of God has to say about each of the two combatants in the spiritual war in which every Christian is engaged: the Holy Spirit and Satan, the Great Adversary. His object is twofold: to help Christians know their enemy, but supremely to enjoy in practice, through the presence and power of the indwelling Holy Spirit, the victory of the Lord Jesus Christ over Satan at the cross. As the author concludes his section on the Adversary, "Scripture throws light on these things, and it is well for us to gain what help we can from it. Not all subjects in Scripture are pleasant, but all are profitable, and for our learning."