The Lucifer Covenant, by Phillip Ellis Jackson and R.A. Varghese

Jackson and Varghese use this idea as the basis for a fast paced action and adventure story steeped in religious significance. The minions of the devil are bent on destroying the remnants of the exorcists for they are the only force that can stop the complete subjugation of the Earth by Satan. An aging, humble simple priest finds himself at the vortex of cosmic forces as he quests to discover the seven secrets that will ultimately defeat evil.

Helped by Opus Dei (Work of God) and his faithful companion Miguel, Father Santos must work assiduously and prayerfully to fulfill his destiny. This book is fast paced, well plotted and thought provoking.