Why then the law?

I. (vv. 15-18)
The inheritance either comes through the law or through the promise — but the inheritance came by a promise (v. 18). It was already promised 430 years ago; whatever the law does, it cannot annul the covenant promise and the law cannot be the means of receiving what was promised!!!!
II. (vv. 19-20)
Paul asks a very important question. If the law doesn't guarantee or provide the blessings, then what was its purpose? "Why then the law?"
ONE: IT WAS TO SHOW SIN
TWO: IT WAS TEMPORARY
THREE: IT WAS INFERIOR
ERGO: We have talked about the law and how rightly to understand it (before). It cannot be our hope. It can only expose sin; can tell me what you ought to do but can't give you the power to do it. It can reveal your sin but it can't suppress your sin. It will never ever give you life.
III. (vv. 21-22)
Paul asks another question here: "Is the law then contrary to the promises of God?" Paul says, "Certainly not." The law was not to compete with the promise; it doesn't contradict it.
Those who know and recognize they are imprisoned in their sin look beyond themselves to Christ. All of sudden He sounds wonderful. God showed the individual his sins. Come to Christ!