«The Darkness of God» by Chris Bunch

Joshua Wolfe has four sworn enemies: the Chitet cult, a power-mad baron, the Federation government, and the alien “virus” that is slowly invading the known universe.

And he has one hope: the Ur-Lumina, the legendary power-enhancing crystal of the vanished race, the Al’ar.

But the Ur-Lumina is in the hands of a ruthless gangster. And Wolfe isn’t on her good list at the moment . . .