'Unless' in the Bible

Therefore, remember how far you have fallen. Repent and go back to what you were doing at first. If you don't, I will come to you and remove your lamp stand from its place unless you repent.

Look! I am going to strike her with illness. Those who commit adultery with her will also suffer greatly, unless they repent from acting like her.

so that no one may buy or sell unless he has the mark, which is the beast's name or the number of its name.