James H. Jackson: The Reaper [2002] paperback

In Rome, the Easter crowds of the devout watch in horror as the Pope is assassinated. In Canada's frozen north a lake is suddenly turned into a cauldron of radioactivity. In the Middle East the search for water ends in a bloodbath. Three events with no connection, no apparent purpose. Except in the minds of an extreme millennial cult hidden deep in the mountain fastnesses of North Carolina, a cult for whom man's abuse of the planet has called down God's punishment, a cult dedicated to initiating a final battle between the forces of good and evil. With a terrifying combination of modern technology, military organisation and religious dementia, they are about to unleash a last crusade that could mean the end of man's reign on earth. And only one man can stop them...