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St. Thomas Aquinas on Justification, pt. 1

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Series Introduction

C.S. Lewis once said, “It’s a good rule after reading a new book never to allow yourself another new one till you have read an old one in between. If that is too much for you, you should at least read one old one to three new ones.... Every age has its own outlook. It is especially good at seeing certain truths and especially liable to make certain mistakes. We all therefore need the books that will correct the characteristic mistakes of our own period.... None of us can fully escape this blindness, but we shall certainly increase it, and weaken our guard against it, if we read only modern books....The only palliative is to keep the clean sea breeze of the centuries blowing through our minds and this can only be done by reading old books.” 1

This principle becomes more evident in our own time. When we peer into those old books of each of our respective traditions, we see something fuller, deeper, more precise than those books of our day. Books today are beggarly in comparison to those of old. They are treasures that have been uncovered. They provide paradigm-shifting perspectives never thought of. The work of our Theological age is not providing “new,” “original,” or “fresh” perspectives as many have taught. Instead, the labor of our age is to labor to uncover those works that have been lost before we even think of building something new.

It is in this spirit that I write this series. Justification has taken a central role in polemical theology over the last five centuries due to the Reformation. Each has taken its narrowly defined side. Before then, Justification took a relatively minor role in the system of one’s theology. This series seeks to show the thought of one of Theology’s brightest lights before the polemics that arose around the Reformation. What can we learn from him? Did he take a side in our modern debate? What did he emphasize that we have missed?

What is Justification?

The first question that Aquinas answered and the first question we must answer is, “what is justification?” St. Thomas answers that “The forgiveness of sins is...justification.” 2 St. Thomas here combines two “changes” into a single “motion.” Justification is the death of sin and the birth of justice (righteousness), only to be distinguished mentally and not really.

This “forgiveness of sins” ought not to be taken in a legal sense. St. Thomas is teaching here that it is truly the eradication of sin in the soul. When the presence of justice eradicates sin, there is also no guilt; a man cannot be guilty of sin that he does not possess.

Justification and Resurrection

For St. Thomas, the death and resurrection of Christ are central to our Justification as to the cause. He compares and contrasts our spiritual death with the bodily death and resurrection in Christ. We are participants in this resurrection and in this death; in Christ, we die to sin, and in Christ, we are raised, given life in our Justification. He writes,

“Most aptly does the Apostle attribute remission of sins to Christ’s death and our Justification to his resurrection, thus tracing out conformity and likeness of effect to cause. As sin is discarded when it is remitted, so Christ by dying laid aside his passible life, in which the likeness of sin was discernible. But when a person is justified, he receives new life; in like manner Christ, by rising, obtained newness of glory. Therefore, Christ’s death is the cause of the remission of our sin: the efficient cause instrumentally, the exemplary cause sacramentally, and the meritorious cause. In like manner Christ’s resurrection was the cause of our resurrection: the efficient cause instrumentally and the exemplary cause sacramentally.” 3

This likeness for St. Thomas is not allegorical; it is participatory. In Christ, we truly die to sin, and in Christ, we are truly made alive again. The death and resurrection of Christ are true causes to the effect of Justification.

Change and Motion

St. Thomas begins his more precise analysis of the nature of Justification by describing the difference between a “motion” and a “change.” A single motion is that whereby a certain accidental quality is lost, and another accidental quality is gained. For example, if we describe a black wall being painted white, we are describing not just a change but also a motion, from black (the loss of blackness) to white (the gain of whiteness).

While change and motion are related, they are distinguished. Change is the coming into or out of being, birthing, or perishing. In the example above, the black wall becoming non-black or the non-white wall becoming white are examples of changes. The motion of a black wall becoming white has two changes, yet described as a whole, it is a motion, with two changes virtually distinguished.

Justification as a Motion

Justification is a motion, not only a change. It is “a motion to justice, just as whitening means a motion to whiteness.” 4 The motion is from sin and to justice. Sin is perishing, and in its place, justice is born. Justification then is “the same as the forgiveness of sins.” 5 The concept of “justification” and “forgiveness of sins” may be distinguished mentally, the former describing “the final term” and the latter “designates it with reference to the starting point.” 6

While it is not formally a change, it may be described as a collection of two changes. The first change is the passing away of sin, i.e., “the perishing of guilt.” The second change is in reference to the generation of justice, i.e., the “coming of justice into being.” From this, we see that while Justification is adequately described as the “forgiveness of sin,” there is more than this happening. Justification is the forgiveness of sin, achieved by “a justice which is opposed to any sin whatever.” 7

Concerning the generation of justice, this can be taken in two ways. The first way is “simple generation,” that is, “from privation to form.” 8 This is not “justification” per se; it is justice being given to someone who neither has justice nor has sin. An example of this type of generation is in Adam. The second way is Justification proper. It is “a transmutation from the state of injustice to the aforesaid state of justice.” 9 This person, like the first, does not have justice but, unlike the first, has the contrary vice of injustice. Therefore, there is a motion “from one contrary to the other.” 10 In light of this, because “movement is named after its term whereto rather than from its term whence, the transmutation whereby anyone is changed by the remission of sins from the state of ungodliness to the state of justice, borrows its name from its term whereto, and is called justification of the ungodly.” 11

What is Justice?

“Justice” can be taken in three ways. The first way is “a specific virtue distinguished from the other cardinal virtues.” 12 This is a natural virtue whereby one is ordered towards the community’s life. This cannot be the “justice” spoken of, for this is not contrary to sin per se but is only contrary to those that hurt the community bond.

The second way it can be used is “of legal differing from virtue only in concept. In so far as virtue directs its act to the common is called legal justice because it upholds the law, as when a brave man fights valiantly on the field of battle for the safety of the commonwealth.” 13 This too cannot be what we are speaking of when we use the word “justice.” For, this only speaks of those virtues which are opposed to sins that are opposed to “the common good” and not to all sins in general.

The third way the word “justice” is used is the “distinctive state in which man stands in the right relation to God, to his neighbor, and to himself, so that his lower powers are subject to the higher.” 14 In another place, this is described as “a certain rectitude of order in the interior disposition of a man, insofar as what is highest in man is subject to God, and the inferior powers of the soul are subject to the superior, i.e., to the reason.” 15 This is the justice in which “every sin is opposed, since some of the order mentioned is destroyed by every sin.” 16


In conclusion, there is a lot to be learned from this definition of Justification by St. Thomas. This type of discourse on Justification is completely foreign to a modern Protestant reader. The word “Justice” rarely gets thrown around in our discourses on Justification. A lot may be drawn from his discussion of Justification as an interior motion caused by the grace of God, focusing on the ontological sense in which the tradition has spoken of Justification.


1. C.S. Lewis, Introduction in St. Athanatius, On the Incarnation

2. QDeVer.Q28.A1.SC

3. CT.BookI.C239.4

4. QDeVer.Q28.A1.C.2

5. Ibid.

6. Ibid.

7. Ibid.

8. ST.I-II.Q113.A1.C.2

9. Ibid.

10. Ibid.

11. Ibid.

12. QDeVer.Q28.A1.C.3

13. Ibid.

14. Ibid.

15. ST.I-II.Q113.A1.C.2

16. QDeVer.Q28.A1.C.3

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