Cunningham:
The most important question, however, connected with this department of the subject, is not whether what Christ suffered was a punishment, or properly penal, but whether it was the penalty which the law had denounced against sin, and to which sinners, therefore, are justly exposed. Now, upon this point, there are three different modes of statement which have been adopted and defended by different classes of divines, who all concur in maintaining the doctrine of the atonement against the Socinians. Some contend that the only accurate and exact way of expressing and embodying the doctrine of Scripture upon the subject, is to say, that Christ suffered the very penalty the same thing viewed legally and judicially which the law had denounced against sin, and which we had incurred by transgression. Others think that the full import of the Scripture doctrine is expressed, and that the general scope and spirit of its statements upon this subject are more accurately conveyed, by maintaining that Christ did not suffer the very penalty, the same penalty which sinners had incurred, but that he suffered what was a full equivalent, or an adequate compensation for it, that His suffering was virtually as much as men deserved, though not the same. While others, again, object to both these statements, and think that the whole of what Scripture teaches upon this point is embodied in the position, that what Christ suffered was a substitute for the penalty which we had incurred.
Dr Owen zealously contends for the first of these positions, and attaches much importance to the distinction between Christ having suffered or paid the same penalty as we had incurred, and His having suffered or paid only an equivalent, or as much as we had deserved; or, as he expresses it, between His suffering or paying the idem and the tantundem. He lays down the doctrine which he maintained upon this point against Grotius and Baxter in this way: “That the punishment which our Savior underwent was the same that the law required of us; God relaxing His law as to the persons suffering, but not as to the penalty suffered.”1 There are, however, divines of the strictest orthodoxy, and of the highest eminence, who have not attached the same importance to the distinction between the idem and the tantundem, and who have thought that the true import of the Scripture doctrine upon the subject is most correctly brought out by saying, that what Christ suffered was a full equivalent, or an adequate compensation, for the penalty men had incurred. Mastricht, for instance, whose system of theology is eminently distinguished for its ability, clearness, and accuracy, formally argues against the death of Christ being solutio “proprie sic dicta, qua id praieise prsestatur, quod est in obligatione”2 and contends that “reatus tollitur satisfactione, qua non idem precise, quod est in obligatione, creditori pnustatur; sed tantundem, seu equivalens.” And Turretine3 seems, upon the whole, to agree with him, or rather, to conjoin the two ideas together, as being both true, though in somewhat different respects, and as not essentially differing from each other. He has not, indeed, so far as I remember, formally discussed the precise question about the idem and the tantundem, on which Owen and Maastricht have taken opposite sides; but in discussing the Socinian argument, that Christ did not make a true and real satisfaction for our sins, because lie did not in fact pay what was due to God by us, and especially because lie suffered only temporal, while we had incurred eternal, death, he meets the major proposition by asserting that there might be a true and proper satisfaction, though the same thing was not paid which was due, provided it was a full equivalent in weight and value, “etsi non idem, modo tantundem habeatur, sufficit;” while lie meets also the minor proposition of the Socinian argument, by asserting that Christ did pay what was due by us; the same, not of course in its adjuncts and circumstances, but in its substance,–His suffering, though temporary in duration, being, because of the infinite dignity of His person, properly infinite in weight or value as a penal infliction, and thus substantially identical, in the eye of justice and law, with the eternal punishment which sinners had deserved.