Why did a moral god kill Nadad & Abihu?

[Fidel_Castronaut]

Also note that God did not impose the law on them. He offered it, with reward if obeyed and punishment if not, and they voluntarily accepted it.

Yes, because the threat of horrible everlasting punishments didn't sway their decision at all. Much in the same way I could offer someone a great deal: Give me your car and I won't stab you. That they gave me their car was completely of their own volition, naturally. :\