For by a single offering he has perfected for all time those who are being sanctified.-Hebrews 10:14
I love this verse. Look at what is going on here. Because of Christ's sacrifice on our behalf and our union with him, we have been perfected for all time. If you are in Christ, you are perfect. Do you see that here? You are perfect. That means no flaws in you. That means spotless. Why? Because of Christ's perfection given, or imputed, to you. If you are a Christian, when God looks on you, He sees Christ. He sees perfection.
Yet, we are also being sanctified. In other words, you are being made holy. You are growing in righteousness. So, in addition to having already been perfected in Christ, if you are a Christian, you continue to grow in holiness. You have not yet arrived at sinlessness in your deeds--you will not in this life--but you will continue to become more Christlike.
This is one of the Bible's mysteries. It is not an either/or, it is a both/and. You are both perfect and growing. Praise be to God.
For more, consider definitive versus progressive sanctification.