Sorry for jumping in... but I am not sure I really believe that Jesus sacrificed anything if the biblical story is to be believed. Jesus was fully aware of his divine nature, he knew he would survive this earthly death and be taken back into heaven - just what exactly is the sacrifice?
I would like to apologise in advance to those that take offence at me even asking the question, as for some this is an affront. I try to liken my point to the popular Christian belief in the rapture, this is an event very much looked forward to, at no point has anyone suggested this is a sacrifice in anyway despite the similarity in concepts.
Another interesting view comes from the Jewish religion. Obviously they believe they are still waiting for the return of the messiah and do not recognise Jesus' sacrifice... and yet they make no blood sacrifice. They believe the Old Testament provides grounds for forgiven of sins without blood sacrifice; this is achieved through prayer, good works, observance and charity; this viewpoint seems pretty sensible given the Old Testament reason used (see here http://www.jewfaq.org/qorbanot.htm). It is difficult to argue with this position; it seems to me the Old Testament implies that by living a good life, observation of the law and prayer forgiveness can be achieved. Now some of the laws may be considered 'odd' by modern standards, but did this really require a human sacrifice to amend?
As a non-believer I still find the whole concept of human sacrifice and blood offerings as payment of 'sins' completely alien to the concept of justice, divine or otherwise... this is without touching on the 'sins of the father debate'. Surely the only person that should be punished and\or make recompense for the 'adamic sin' would be Adam? I always struggle to understand why so many are so willing to accept that a third party can absolve them of their sins or make up for the original - nowhere else would they ever accept such a concept. If the mother of a murderer offered to sacrifice herself on account of her son's wrong doing to allow her son to walk free - would that be justice?