Is the law then contrary to the promises of God? Certainly not! For if a law had been given that could give life, then righteousness would indeed be by the law. But the Scripture imprisoned everything under sin, so that the promise by faith in Jesus Christ might be given to those who believe.
The law was a temporary bandage until Christ fulfilled all things on our behalf. Is the law contrary to the promises of God? Is the medic on the battlefield contrary to the doctor at the MASH unit who will perform surgery on the wounded soldier? Of course not!
If the medic could impart life, would he? Surely he would, but he does not have the ability, just like the law does not have the ability to impart life. If it could, it would, and Christ's sacrifice becomes unnecessary.
I find the phrase "But the Scripture imprisoned everything under sin" to be fascinating. Could it mean that "that which was written (the law) entrapped us in disobedience, so that the promise, through the fidelity of Christ, can be granted to those to whom it has been entrusted ."?
Any Greek scholars out there?