Duuude, I know you're Christian and all, but I just don't understand the whole "soul" thing anyway. Having one doesn't make you Not Evil, and as Spike shows, not having one doesn't impair your ability to feel love or compassion or have a kickass personality.
The whole "quest to regain soul" thingy is all just a big Yellow Brick Road in my opinion... the Tin Man had a heart all along, all he needed was for someone to tell him so.