The Last Guardian (Electronic book text)

In 1975, the life of Cornell graduate student T.G. Shass is forever changed when he finds himself in possession of a mysterious and ancient artifact. Unable to remember how he acquired it and powerless to rid himself of it, T.G. is soon shaken not only by the object's presence, but by a chilling encounter with evil and a jarring journey to another world.
He was the most unlikely of all prophets.
His was the most critical of all missions.
Upon his return, T.G. discovers that Earth is no longer the home he knew. His sweetheart, Jenni, is missing, and all evidence indicates that she's been caught up into the macabre, unnatural realm he's just departed.
His determination to find Jenni overrides the bitter aftertaste of his otherworldly experience, and T.G. seeks a way to go back. But his second journey holds far more than he imagines. Can T.G. fulfill his key role in God's plan to defeat the forces of darkness? Or will his imperfect faith lead to destruction as the last days draw to a climactic end?

"From the Trade Paperback edition."