“Can the Ethiopian change his skin or the leopard his spots? Then also you can do good who are accustomed to do evil.”
Jeremiah uses images from nature everyone recognized — skin and spots — to make the obvious answer impossible to dodge: no, that doesn't change on its own.
'Accustomed to do evil' describes something repeated so long it no longer feels like a choice — it has become pattern, almost second nature.
Jeremiah is describing Judah's actual condition in that moment — how hard change really is — not decreeing it impossible forever with God.
If changing your own skin were within reach of willpower, the verse would lose its point — it points to a need only God can meet.
If you can't change on your own what has become habit, that's not cause for despair — it's the invitation to stop trying alone and ask God for a new heart.
Act: Name one sin pattern that already feels automatic in you, and pray today specifically asking God to do what you cannot do alone.