Yes. Every sin you will ever commit was still future when Christ paid for it. Forgiveness is not a balance you top up after each failure. It is a finished transaction you already own.
The Grace Answer
Behind this question is a picture of God with a ledger, crediting you when you behave and debiting you when you slip, so that your standing rises and falls by the day. It is an exhausting way to live, and it is not the gospel.
When Christ died, none of your sins had been committed yet. Every one of them was future. So when Scripture says “He has perfected forever those who are being sanctified,” it means the offering covered the whole timeline in one motion. He did not forgive the sins you had confessed by Tuesday and leave the rest pending. He forgave all trespasses, past, present, and future, and He said so.
Paul spelled out the mechanism in Colossians. God made you alive together with Christ, “having forgiven you all trespasses, having wiped out the handwriting of requirements that was against us.” The record of debt was not merely paid down. It was wiped out and nailed to the cross. You cannot owe on an account that no longer exists.
This is why the New Covenant carries a promise the old one never could: “their sins and their lawless deeds I will remember no more.” God is not keeping the running tally you fear He is keeping. The sin you committed this morning did not surprise Him and did not change your standing, because your standing was never built on your performance. It was built on His.
This is also why your feelings are such an unreliable gauge here. After a failure you feel dirty, distant, disqualified, and you assume the feeling is reporting your actual standing with God. It is not. Feelings track your sense of things; they do not move the finished work of Christ an inch. What He accomplished stays accomplished whether you feel forgiven on a given morning or not.
None of this makes sin harmless or trivial. Sin still wounds you and the people around you, and grace will never pretend otherwise. But it cannot un-forgive you. You do not sin your way out of a gift that was given before you were born, purchased in full, and sealed by the word of a Father who does not lie.