Why is Christ's death considered a sacrifice?

[John V]

Define "sacrifice" or go away alpha.

Sure.
http://www.merriam-webster.com/dictionary/sacrifice

Some definitions and examples which go beyond the narrow definition you insist on:

the act of giving up something that you want to keep especially in order to get or do something else or to help someone (the first definition given)

No sacrifice is too great when it comes to her children.
He made many personal sacrifices to provide help to the city's homeless people.

And no sir, you haven't read your Bible AT ALL. HE GAINED EVERYTHING. HE WAS REWARDED HANDSOMELY AFTER DOING HIS DEMENTED FATHER'S WILL.

Er, no, he was God before, and God after. You act as if he were a normal mortal man given a great reward. Read the Bible - that's not the case.