“Asking for forgiveness through faith alone is not enough. Our Lord clearly shows that we must also, by his grace, remove the disorder of the heart that causes us to sin against both God and our neighbors. If this is not accomplished here, then God will finish this operation in Purgatory.”
“But when Christ had offered for all time a single sacrifice for sins, he sat down at the right hand of God, waiting from that time until his enemies should be made a footstool for his feet. For by a single offering he has perfected for all time those who are being sanctified.” - Hebrews 10
Perfected. Not partial. “Perfected for all time.”
“But God, being rich in mercy, because of the great love with which he loved us, 5 even when we were dead in our trespasses, made us alive together with Christ—by grace you have been saved— 6 and raised us up with him and seated us with him in the heavenly places in Christ Jesus...” - Ephesians 2
Notice the tenses: “made”, “Raised”, “seated”. Jesus is there, and so are we if we are “In Him”.
Hence, “It is finished!”
You are conflating forgiveness with cleansing.
Hence, “It is finished!”
What was finished was the new paschal sacrifice which began at the Last Supper. If we were to take these words in an absolute sense the you would also have to say that faith itself is not necessary. Requiring this would also be adding to the saving work of Jesus.
I would also note the common Protestant tactic of quoting another scriptural passage while ignoring scriptural passages (in this case that of Jesus himself) which go against Protestant teaching.