Before Good Omens has even started, officially, on page xiv in my copy, there's a list of characters. These include...
Metatron (The Voice of God)
Satan (A Fallen Angel; the Adversary)
Crowley (An Angel who did not so much Fall as Saunter Vaguely Downwards)
ADAM (An Antichrist)
Pepper (A Girl)
Wensleydale (A Boy)
Brian (A Boy)
As can be seen, the only two characters to have their names entirely capitalized are DEATH and ADAM. (Not even God gets entirely capitalized.)
Why is this? Why is Adam's name entirely capitalized here, even if he is the Antichrist, when even such characters as Satan and God don't get this same treatment?