Originally posted by: DAGTA
During the old covenant (Old Testament times), sin had to be atoned for with blood. Since humans didn't want to die, God was willing to accept animal blood for the atonement of sin. That was the reason for so much animal sacrifice. However, it wasn't enough and God knew people needed something easier and better.
God sent Jesus, his perfect son. Jesus did many things for us... he lived an example of a life dedicated to God, he taught us many great morals and ideas, etc. However, the most important thing Jesus did for us was to serve as the ultimate sacrifice for sin. Jesus died without sin and gave his life and blood as atonement for all the sins of the world, past, present, and future. In order for his sacrifice to cover the sins of a person, that person need only accept Jesus as his savior and believe. That does not mean everyone has a free ticket to sin... we all will still answer for our sins. The difference is that with Jesus taking the cost of the sin upon himself, we don't have to die or be separated from God forever because of our sin. It's paid for, but we still need to repent and try to avoid sin.