Acts 13:.38-39

Acts 13:38-39 - Therefore, my brothers, I want you to know that through Jesus the forgiveness of sins is proclaimed to you. Through Him everyone who believes is justified from everything you could not be justified from by the law of Moses.

So in life we live by the law. We do our best to be obedient to it and to do what is right. If we break the law we know there will be consequences. We might be able to continue on like this for awhile, but inevitably we will mess up. Now what happens? According to the law of Moses when you sin you deserve death.
God is a just God and cannot tolerate sin. Therefore a price had to be be paid for our sin. Before Christ the Jews used animals as a temporary covering for their sin, but that would not last. A permanent sacrifice had to be made.

Jesus was that sacrifice. He was perfect, without spot or blemish; He had no sin. When He died He took all sin upon Himself and paid the permanent price for it. No more animals were needed.

Through Jesus the forgiveness of sins is proclaimed to you and me. We are now justified through Christ and can stand before God purified.

If compare the two we see that the law of Moses only provided a temporary covering for sin, while through Christ our sin is not only covered, it is completely washed away. You have complete and permanent justification through Him as long as you accept it.