a sacrifice is giving something up. in many religions, it usually is about giving something to god or gods. many pagan peoples made human sacrifices and animal sacrifices. the greek play "iphigenia" by euripides contains an example of this. in the old testament, jewish people followed the laws about animal sacrifices in the book of leviticus. cows and pigeons were killed to make atonement with god. in the new testament, christ's death on the cross is seen as substitutionary atonement for sin.