It was a perfect sacrifice by a perfect person to perfect some very imperfect people. By that single offering, he did everything that needed to be done for everyone who takes part in the purifying process. The Holy Spirit confirms this:
This new plan I’m making with Israel
isn’t going to be written on paper,
isn’t going to be chiseled in stone;
This time “I’m writing out the plan in them,
carving it on the lining of their hearts.”
I’ll forever wipe the slate clean of their sins.
Hebrews 10:11-18 MSG