Those who are religiously minded will tell you that only the sins you committed before you received Jesus Christ into your life are forgiven. Any other sin from then on must be confessed before you receive forgiveness. But that is not true because Christ died before there was any one sinner on the face of the earth. All of our sins occur in the future, after we are born, but Jesus has already died and washed them away. On the day you gave your life to Christ, all of your sins were forgiven: past, present, and future. Does that mean that you have never sinned since then? No! But God has punished everyone in Christ: His death, burial, and resurrection paid fully for us.
Note that there are sins outside the big ten mentioned in Exodus 20: thou shall not have another god, thou shall not steal, thou shall not commit adultery, and so on. According to the scriptures, anything done outside of faith is sin. And when Jesus came, he raised the bar. He said adultery is not only the act of sleeping with a person who is not your spouse but also includes lusting after another. God raised the bar to show you that you cannot keep the law; that leaves you with no other option but to live under grace.
The purpose of the law is not to make us perfect but to expose sin. And where sin abounds, much more grace abounds (Romans 5:20). God wants you to live under grace but if you decide to still operate under the old ordinances, you are following inferior commands. Grace is an elevated platform. Grace will allow you to sin less because sin shall not have dominion over you. This is because you will no longer be under the law but under grace. In other words, if you live under the law, sin will have dominion over you for “the strength of sin is the law” (1 Corinthians 15:56, KJV).