As one might expect, it's worse in Hell. Mephistopheles, who ranks next under Lucifer, is supposed to be best buddies with Beelzebub. According to celestial gossip, the two are plotting a junta against their boss. Yet--no surprise really, considering they've chosen evil over good--they don't get along so well, either. At one point Beelzebub even rapes Mephistopheles. The scene is graphic, although Jane Lebak's artful writing manages to keep its skirts a smidgeon above the mud.
There are people in Annihilation, too. They're dead and in Heaven, of course. The only one who has a major supporting role is Mary, Mother of Jesus. She serves as a cook, mostly, but provides succor to the ailing and offers earthly common sense suggestions when the angels get tangled in ethereal complications. Mary often distracts arguments with freshly baked cookies, if any are left after her son snitches them off the tray.
Annihilation is a dazzling, sophisticated adventure story told by a writer who possibly either has memorized the Bible or has a divine imagination. I suspect the answer lies somewhere in between. My only superficial familiarity with things biblical prevents me from addressing the first with authority, and my own imagination shrinks to clichés in the presence of Lebak's. But good writing always seduces me, and I love a good story.
I venture even smirking atheists will enjoy Annihilation. The only readers I would caution to take a deep breath before entering this magical world with its many shades of good warring the darkest tones of wickedness would be those with an irony deficiency, i.e. an anemic sense of humor. I laughed out loud too many times to count, surely worrying folks at the laundromat next door. I also would advise reading the Archangel's introductory note, which explains the hierarchy of angels and the special skills each tier commands. I missed it when I started reading, and found it only after becoming so confused with the cast of characters I sought help in the table of contents. Save yourself the trouble.