If you're taking the Buddhist perspective aren't you supposed to question the Buddha?

As near as I can tell the origins are in Sanskrit so that's where I begin. It's not hard to follow it through in the cross-pollination of cultures and religions. What's interesting for me is that every religion was right for that culture at that time so when you put the word in context it makes more sense. Semantics aside, karma - or at least a version of it - is common to most religions and the only real differences there are are the ones we choose to make. Today the Law of Karma is 'portrayed' as reward, punishment and/or revenge mentality so there's an insight into what that reflects.