The Roman Catholic notion of the donum superadditum (superadded gift) teaches that, at creation, God created man––body and soul. But because creation requires the gracious sustainment of the Creator, it would, in theory, slip off into non-being (non-existence) without His adding sustaining grace. Therefore, man in his essential parts––both body and soul––are in conflict with one another and require the superadded grace of God in order to be brought into harmony. Richard Muller writes:
superadded gift; specifically the gift of grace superadded to human nature after creation but before the fall, a concept debated in the medieval theory of grace and merit and rejected by the Protestant orthodox. The concept arises out of the problem of explaining the hypothetical ability of Adam and Eve to have retained their original righteousness.
Some have rejected this idea altogether since it apparently contradicts the biblical data. Scripture states that God made all things good (Gen. 1:31). But this wholesale rejection of the superadded gift is based on a confusion between what God has made on the one hand, and how God made it that way on the other hand. What God made was good. The Roman Catholic could still agree right before adding, or course, that God made it good by way of His superadded gift of grace.
Now, I’m not agreeing with the Roman Catholic here, I just want to caution against the folly of rejecting the notion of a creational gift of grace which is purposed to sustain creation in its existence, without which it would chaotically spin out of being. We need to be careful to reject the notion of the superadded gift for the right reasons. According to the Reformation and even Thomas Aquinas, the notion of a superadded gift is fundamentally flawed at the more nuanced levels of the discussion.
Whereas historical and contemporary Roman Catholics might see the creational gift as added to creation logically after God spoke it into existence, men like Aquinas and the Reformers would see the gift as that which was given in and with the creation itself rather than being added post hoc. It was a donum intrinsecum, or an intrinsic gift. Instead of a donum superadditum, classical Protestants would see a donum concreatum, that is, a gift given by God, inherent in creation itself.
Why Is a Gift at Creation Necessary?
Some would accuse classical theists of being gnostic for saying creation is, by itself, imperfect. But this is not the case at all. There are some important things to consider before jumping to accusatory conclusions. Gnosticism holds that matter is evil just in virtue of being matter. There are several reasons why the gnostic notion of evil matter drastically differs from the classical notion of a creational gift being necessary for the world’s existence. First, in one sense, anything that is not God is imperfect insofar as it is not that being than which nothing greater can be conceived. Creation is not God––who is perfection itself. But this is not to say matter is intrinsically evil; it just isn’t God.
Second, in another sense, creation is perfect insofar as it fulfills the end which God intended it to fulfill. A dying tree is imperfect because it is not properly functioning the way God intended it to function. We may distinguish between these two types of perfection––the former is an ontological perfection according to which God alone may be considered; the second is a teleological perfection which is dependent upon God’s decree and providence.
Third, something lives and fulfills its end only as God sustains it. We can think of this in terms of humanity. If God withdraws His grace in one area of society, sin abounds mores than it does when the opposite is the case. Grace is required in creation for there to be harmony or it becomes that which it was not intended to be.
For these reasons, a gift of God’s grace must accompany creation in order for it to remain and function according to its created ends. But this gift is not merely added to creation, it came with creation. Creation and the donum concreatum is a packaged deal, not two separate works of God.
The Donum Superadditum and Infused Grace
Following from the above, one has to wonder how relevant the notion of infused grace is to the donum superadditum. After all, it is this superadded gift which was lost at the fall and, consequently, it must be obtained once again by participation in the sacramental system of the Roman Catholic Church. This is not the case with the concreated gift. At the fall, Adam––and all his posterity––lost the iustitia originalis, or original righteousness. Unlike the superadded gift, the gift of original righteousness (iustitia originalis), cannot be re-obtained by virtue of sacramental participation, but must be given by a special act of God’s grace. Muller writes:
By extension, the loss of the iustitia originalis in the fall was the loss of something fundamental to the constitution of man that could be resupplied only be a divine act and not, as the semi-Pelagian tendency in late medieval Scotism and nominalism indicated, something superadded that could be regained by a minimal act of human obedience.
Thus, for classical Protestants, it is counter-intuitive to say that one who has lost their original righteousness can––provided they put forth enough effort––merit back that original righteousness by participating in the sacraments and thereby receiving infused grace. Rather, that which was lost at the fall must be granted by God as He graciously acts in the sinner to regenerate their heart and renew their spirit, all according to His will.
 Richard A. Muller, Dictionary of Latin and Greek Theological Terms, (Ada: Baker Academic, 2017), 95.
 Ibid., 96.
 Also, for reference see, https://amfortress.wordpress.com/2015/03/07/donum-superadditum-donum-concreatum/?fbclid=IwAR0VfjptpVR-POekpq8JmR8zZZU5tYuuOddTotw9E_fImRjb6tvFCwhb234