Old vs New

The Old Covenant:
"Now therefore, if you will indeed obey My voice and keep My covenant, then you shall be a special treasure to Me above all people; for all the earth is Mine."- Exodus 19:5

The old way was for the people to keep the law of God, in this way the people were ruled under the law. They had to obey everything the Lord had commanded or else they would be punished, to atone for their sins a sacrifice was to be made to God.

The New Covenant:
"But the Scripture has confined all under sin, that the promise by faith in Jesus Christ might be given to those who believe. But before faith came, we were kept under guard by the law, kept for the faith which would afterward be revealed. Therefore the law was our tutor to bring us to Christ, that we might be justified by faith." - Galatians 3:22-25

When Christ came, the new covenant began, which meant that we are now living in the grace of God. Jesus came to become the ultimate sacrifice that whatever sins we have done (whether big or small) is forgiven.

God knew that it would come to this, that man would not obey His words, that His law would be rejected. This was all planned out that God even after His own people rebelled, He still loved them and cared so much about us that He went to the extent of sending His own son to set us free.

God no longer looks at your sins, whatever things you've done in the past. When you accept Jesus, the only thing God sees is the blood of Jesus that covers you. God is not a God of the past, He is a God of the present and the future.