'Unless' in the Bible

So remember the heights from which you have fallen, and repent [change your inner self—your old way of thinking, your sinful behavior—seek God’s will] and do the works you did at first [when you first knew Me]; otherwise, I will visit you and remove your lampstand (the church, its impact) from its place—unless you repent.

Listen carefully, I will throw her on a bed of sickness, and those who commit adultery with her [I will bring] into great anguish, unless they repent of her deeds.

and that no one will be able to buy or sell, except the one who has the mark, either the name of the beast or the number of his name.