Undead are supposed to be Amadia's champions regardless of subrace, but the game is bugged to occationally mention the subrace god as the main god instead. Happens with Undead Lizards, probably with Dwarves and Elves too.
What happens is the Story sequences know your actual race, but dialog is based on tags and undead have both "Undead" and subrace tags. If you use the mask your god will even change to the mask race god in dialog. I say this is a bug because you only have the one god in you and it doesn't change regardless of your appearance.
