Law and Gospel in a Nutshell

Now Scripture sets forth two kinds of teaching—Law and Gospel. The Law, in condemning sins and setting forth the gravest threats of God, is that hammer (Jer. 23:29) through which God breaks rocks, that is crushes the spirit, renders the heart contrite and humbles it, so that truly and earnestly acknowledging the multitude and magnitude of sins and of the wrath of God over sin, the mind begins to hate and detest sin, to fear the wrath and judgment of God so that it is unwilling to perish eternally under them but sighs and struggles with groaning that it may be freed from them. There the Law indeed has and sets forth promises of life, but on condition of perfect fulfillment… The Gospel, however, teaches that what was impossible for the Law on account of the flesh, God provided by sending His Son (Rom. 8:3). Therefore it shows Christ, the Lamb of God, born under the Law for us, in order that He might make satisfaction to the judgment of God, revealed in the Law, by His obedience and suffering on our behalf. This Mediator the Father sets before us in the Gospel as a propitiation by faith in His blood through the remission of sins (Rom. 3:25). “For this is the will of the Father, that everyone who believes in the Son should not perish but have eternal life” (John 6:40). Thus the Gospel proclaims, offers and sets before contrite and terrified consciences the grace of God, reconciliation and remission of sins freely on account of the merit of Christ; and it is His will that everyone should lay hold of and apply this benefit of the Mediator to himself.
- Martin Chemnitz