And in the final sanctification/purgatory we are purified solely by Christ. Christ does the saving. We are purified by the blood of the Lamb, by the power of the Holy Spirit
We'll have to disagree on that one. I believe there are also two Baptisms. One is part of public profession of faith and the other is the one of salvation Baptism by the Blood Of Christ the instant we accept Christ as Lord and Savior. At that time we are under Grace and no longer condemnation.
Matthew ch 3 11“I baptize with£ water those who turn from their sins and turn to God. But someone is coming soon who is far greater than I am—so much greater that I am not even worthy to be his slave.£ He will baptize you with the Holy Spirit and with fire.£ 12He is ready to separate the chaff from the grain with his winnowing fork. Then he will clean up the threshing area, storing the grain in his barn but burning the chaff with never-ending fire.”
The never ending fire. That is a mighty long purification. As hard as we may try {and BTW we should try not too sin} we can not overcome our sins alone even after salvation. To have to go beyond having to have our sins or imperfection purified or re-washed after that point re-crucifies Christ. It can't be done. At the acceptance of Christ as Lord and Savior our sinful being is dead and with it the sins. At that point till we leave this world in death. Our sins before and after receiving Grace are too be cast into the lake of fire at the end time.
But how can Christ forgive the sins you commit afterward? He already has. Before you were born GOD knew the total sins of your life before and after. He knew after salvation you would clock out 5 minutes early staling money from your employer. He knew the name and curse you would give to the guy who cut you off driving home on the road. He knew you would lie to aunt Ethel about her new dress. He knew you would be angry at Joe up the street who got the promotion you didn't. He already knew and he has already forgiven. Imagine such a loving GOD that even though He knows before you even existed He still forgives you unconditionally if you accept His plan of salvation. Yes He also knew before they were born those who would forever be against him like Herod, Pharaoh, and many others. He knew and He told His children if you call on the name of My Son Jesus Christ in earnest for your salvation and forgivness of your sins I will forgive you now and forever your sins and you will be healed.