'Unless' in the Bible

And he said, "So how could I, unless someone will guide me?" And he invited Philip to come up [and] sit with him.

And some men came down from Judea [and] began teaching the brothers, "Unless you are circumcised according to the custom [prescribed] by Moses, you cannot be saved."

Paul said to the centurion and the soldiers, "Unless these [men] remain with the ship, you cannot be saved!"