Question:
How do we know that Jesus forgives the sins of the future?

Answer:

1 Peter 1:3:  “Blessed be the God and Father of our Lord Jesus Christ, who according to His great mercy has caused us to be born again to a living hope through the resurrection of Jesus Christ from the dead.”  1 John 1:9: “If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness.”  Colossians 1:20:  “And through Him to reconcile all things to Himself, having made peace through the blood of His cross; through Him, I say, whether things on earth or things in heaven.”  And Colossians 2:13: “When you were dead in your transgressions and the uncircumcision of your flesh, He made you alive together with Him, having forgiven us all our transgressions.”

The book of Romans tells us that Christ “condemned sin in the flesh” (Romans 8:3) when He bore the wrath of God against our sins. God was satisfied with the work Christ did on the cross for He raised Him from the dead and received Him to His own right hand in the glory. So our sins will never be brought up by God against anyone who trusts in Christ!  How many of the sins that Jesus bore on the cross were future sins?  ALL OF THEM!