Are all my sins already forgiven, including future sins?
Yes. Scripture teaches that in Christ believers are forgiven now and forever. Paul writes that God made us alive together with Him, having forgiven every trespass we did commit, are committing, and will commit. Christ died for all the world's sins and tasted death for every man.
Les explains that this forgiveness does not stop at a certain point in time; it means now and forever you're forgiven. Turning to Colossians 2, he notes Paul writes that while we were dead in sins and in the uncircumcision of our flesh—our pre-salvation existence and pagan Gentile condition—God quickened us together with Christ. When Christ died, we died; when He arose, we arose to newness of life. Having been made alive together with Him, we are forgiven every last trespass we did commit, are committing, and will commit. They are already forgiven. Les stresses that when Christ died, He died for all the world's sins and tasted death for every man.
And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;