Jesus has done the work for us. He is the final and perfect atonement for our sins. He has done everything the Law, which was given to the Israelites thousands of years earlier, had required:
Romans 10:4 For Christ has already accomplished the purpose for which the law was given. As a result, all who believe in him are made right with God.
This is what Jesus meant when he said He came to fulfil the Law:
Matthew 5:17-18 Don’t misunderstand why I have come. I did not come to abolish the law of Moses or the writings of the prophets. No, I came to accomplish their purpose. I tell you the truth, until heaven and earth disappear, not even the smallest detail of God’s law will disappear until its purpose is achieved.