The Naked God

From back cover Warner paperback November 2000:

RETREAT OF THE RESURRECTION

Faced with an interstellar war in which the only weapon is exorcism, the Confederation dissolves into anarchy. For in a desperate act of triage, a few wealthy worlds prepare to sacrifice the mass of humankind to the risen dead souls from the Beyond. Meanwhile, the Possessed are destroying whole planets as they flee the universe in a transdimensional quest to find Heaven.

But there are far worse things than death -- or resurrection. And the Possessed are about to discover that chasing paradise is the most horrific, irrevocable mistake they could make.