You start at 0 XP, level 1. You choose your class and earn a tiny amount of XP before leaving CK. So why argue? The protagonist, though locked up in a dusty library, might be budding tree-hugger, back-stabber or uncouth youth (Barbarian).
As a child of bhaal, it seems you can turn your powers to just about anything. As for godhood, its not just priests with godly powers - every class gets bhaal powers.
I think the races are a little restricted however. How could a half-orc survive Baldur's Gate? How can a dwarf/elf be 20?
But that's not say you can't roleplay as anyhing. Face it, Gorion gets snuffed out at the start of Ch1 in BG and I forgot about him pretty quickly (even though he has the annoying habit of coming back
So play your dual katana wielding gnome wizard slayer for all I care.