NOT "ALL" SINS WERE FORGIVEN ON THE CROSS.
The Gospel of Jesus Christ says:
All sins of all people were forgiven for all time on the cross of Jesus Christ, except for the sin of unbelief that Jesus is the Savior. Did you know this?
It was Jesus' blood, not your faith that brought forgiveness. This doesn't minimize faith, rather it directs your faith to its source...Jesus Christ. The sin of unbelief is the eternal sin that will never be forgiven. Unbelief is the sin commonly referred to as the "unforgivable sin," in the Bible it is called "blasphemy against the Holy Spirit."
The Holy Spirit is convicting the world concerning sin because the world does not believe in Jesus Christ as their Savior. If you reject Christ, you reject the work of the Holy Spirit and "blaspheme" Him!
In your spirit, you are free from sin forever, even if you struggle with sin coming from your mortal flesh, as a Child of God you're free!