Love Is Stronger Than Evil — Kathryn Meyer Griffith

An ancient demon lies trapped behind the stone walls of an Incan cave prison; for centuries it had demanded blood sacrifices, and had schemed to escape. Then it discovers a pathway into the world of men, forging itself into a malevolent and cursed killing object, and making itself capable of giving misery and bringing death to all who touch it. Through decades it torments, destroys, the lives of the unlucky people it comes into contact with until a loving married couple, Emily and Sam Walters, have enough love and faith–and the help of a mysterious priest who's much more than he appears to be–to fight against, and destroy the ancient evil forever…and to finally send it back to hell where it belongs. (Originally a Leisure mass market paperback titled Blood Forge; and later as Blood Forged.) ***