Things start to go backwards when Jesus gets involved.
If you read the Old Testament you’ll notice that the unclean always infects the clean. Not the other way around.
If a clean person touches a carcass or eats an unclean animal, they’re unclean. If they touch an unclean person, they’re unclean. If they commit adultery, they’re unclean.
If they worship false Gods, they’re unclean.
That’s one reason why God instructed Israel to wipe out foreign, pagan nations. If Israel intermingled with pagans, Israel would become unclean. The hearts of the Israelites would be seduced away from the true and living God.
The unclean always infects the clean.
Which is a massive problem, because all of us are unclean. Filthy thoughts and desires swirl in our hearts. Bitter words drip from our lips. Is there any way for us to be clean?
But when Jesus gets involved, things are different.
Jesus touches a leper, and the leper becomes clean. He touches the dead body of a little girl, and the little girl is raised. And he touches sinners, and they are forgiven. Unfaithful adulterers, greedy tax collectors, tanked drunkards. All forgiven. The unclean made clean. Christ is full of such purity and power that he can cleanse the unclean.
Jesus still makes sinners clean today. Like me and you. Aren’t you grateful?