"Many theologians have maintained that justification means 'to make righteous'. They assert that the term points to a change in men, so that, by the grace of God, they become the kind of people they ought to be. This is to confuse justification and sanctification. The very way we use the term ought to put us on our guard against this error. When we speak of justifying an opinion or action we do not mean that we change or improve it. Rather we mean that we secure a verdict for it, we vindicate it. And just as the English verb has nothing to do with changing for the better so is it with Greek verb. It signifies 'to declare righteous', 'to acquit', and not 'to make righteous'. While it is true that the justified man will be deeply concerned with holy living, it is also true that justification is not simply another name for his holy life. It refers to his standing before God, to God's acceptance of him."
--Leon Morris, The Cross In the New Testament, p.241-242