“We are creatures whose Creator needs no justification. Nevertheless, this Creator seeks justification in his words given to sinners (Psalm 51 and Romans 3). But there are two separate justifications. The first justifies according to the law (which holds among humans awhile), but does not suffice before God–indeed that law was used to kill God’s only begotten Son when he came into the world. The second kind of justification is Christ who gives himself to his opponents in the form of a simple promise: I forgive you. These two justifications are called law and gospel, and distinguishing them is the Lutheran passion on earth. The slogan of this way of doing theology is: The Law! . . . until Christ! (Galatians 3:4). God justifies himself by justifying sinners in a simple word.”
Steven Paulson, Lutheran Theology (pg.5)