The Fallen: Book 1-Dark Genesis

None of us could have fathomed that one day our time would be up. That day is now.
Everyone knows of the story of Armageddon, the battle between the forces of Heaven and the demonic legions of Hell. And we all just figured it was a no-brainer, which side would come out on top. But we were wrong.
Journal of Alisha Grace-
Every time I go to the window, I smell only blood, fire, and brimstone. It happened so quickly that no one had time to react: portals forged from demonic magic opened all over the world, and pouring through them were agents of macabre death, tidal waves of destruction the likes of which we had never seen. The sky filled with beautiful, white-winged creatures full of deadly grace and determined precision, intent upon stopping the demon armies. The final war had been brought to our very doorstep.