The verse that you have quoted says that those who are truly Christians will strive to stay away from sin in order to please God, as opposed to false Christians who will continue to sin just as they used to do before being called by the Lord. However this verse doesn't tell us that we are free from sin. Haven't you hear the prayer that Jesus taught us? It says this
“Pray then like this: “Our Father in heaven, hallowed be your name. Your kingdom come, your will be done, on earth as it is in heaven. Give us this day our daily bread, and forgive us our debts, as we also have forgiven our debtors. And lead us not into temptation, but deliver us from evil.” (Matthew 6:9-13)
When you pray to God, do you never ask forgiveness for your sins?