In his Summa Theologica, Aquinas clearly stated his view that the sacraments perform their work through a virtue in themselves. He also stated unequivocally that the sacraments confer the new birth, justification, the grace of the Holy Spirit, sanctification, inward enlightenment, the washing away of guilt, and forgiveness of sins on every person who partakes of them.
From time to time, I come across articles by Reformed authors wherein they encourage the reading of the Summa Theologica by Thomas Aquinas. Their rationale is that Aquinas is an excellent guide for making fine distinctions on theological points. Au contraire. As one who spent several weeks at a nearby university library reading through the unabridged three volume set of the Summa Theologica while writing Historic Christianity and the Federal Vision, I must respectfully dissent from that position. Thomas Aquinas is no safe guide for Protestants. He might be the favorite Schoolman of many Reformed authors, but he should not be in my opinion.
Someone might ask why I was reading Aquinas in my research concerning the errors of the Federal Vision. For one thing, many of the Federal Vision authors (e.g., Peter Leithart, Steve Wilkins, and Doug Wilson) refer to the help they received from Aquinas’ writings in developing their false system. I read the Summa Theologica to see what it was that inspired the Federal Vision authors. As one who has made the experiment myself, here is why I encourage you not to read Thomas Aquinas. Or, if you do read him, read with your eyes wide open and with a discerning and discriminating judgment. Certainly there are some good things in Aquinas’ writings, but there are also a lot of bad and erroneous things as well.
First, Aquinas did not believe in Sola Scriptura. The purpose Aquinas had in writing Summa Theologica was to combine the theology of the Scripture with the theological systems of the ancient Greek philosophers. There are times he begins his investigation of a theological issue with a quote of Scripture (though more rarely than one would like). More frequently, he will begin with a quote from Augustine. Yet, on other occasions he will start with a quote from one of the ancient philosophers. For one who believes in Sola Scriptura, it was very disconcerting to read such an approach to theological issues. The ancient philosophers are in no wise on the same ground as the inspired authors of Scripture.
Second, Aquinas is usually characterized as an Augustinian scholar, but I think that is a misrepresentation. It is true that Augustine had once made the same mistake as Aquinas of seeking to synthesize Scripture with the teaching of the ancient philosophers, but that was during his younger days. The mature Augustine, who stood like a bulwark against the heresy of Pelagianism, had arrived at a position that Scripture was the alone special revelation of God.
Augustine’s theological system was progressively developing until he reached a mature faith. Along the way he cast off his former errors- one of which was concerning salvation that was very close to the Pelagian heresy, which he so effectively combated for the good of the church. Pelagius, like Aquinas and the younger Augustine, also sought to synthesize Scripture with the systems of the ancient philosophers. Many of the heresies of the early church were from the writings of the philosophers, particularly concerning the false ideas on the will of man. Because Aquinas tried to synthesize Scripture (and Augustininaism) with the teachings of the philosophers (even as Pelagius had also tried to do), it is more appropriate to classify Thomism as Semi-pelagianism. In fact, a thorough reading of the Summa Theologica reveals how frequently Aquinas departs from the views of Augustine.
Third, the theological system of the Council of Trent is virtually the same as the conclusions of Aquinas in his Summa Theologica. For instance, Pope Leo XIII in 1879, made the following comment about Aquinas’ influence on the Council of Trent:
The Fathers of Trent made it part of the order of conclave to lay upon the altar, together with sacred Scripture and the decrees of the supreme Pontiffs, the Summa of Thomas Aquinas, whence to seek counsel, reason, and inspiration.
If you like the Council of Trent and Catholic theology, you will love Thomas Aquinas. In fact, you will be delighted with the Federal Vision and the New Perspectives on Paul, as well.
Fourth, Aquinas clearly departed from Augustine on the depravity of mankind. Aquinas denied that human reason is fallen. In Escape from Reason, Francis Schaeffer puts his finger on the problem with Aquinas’ theology:
In Aquinas’ view the will of man was fallen, but the intellect was not. From this incomplete view of the biblical Fall flowed all the subsequent difficulties. Man’s intellect became autonomous. In one realm man was now independent, autonomous.
This sphere of the autonomous in Aquinas takes on various forms. One result, for example, was the development of natural theology. In this view, natural theology is a theology that could be pursued independently from the Scriptures.
From the basis of this autonomous principle, philosophy also became free, and was separated from revelation. Therefore philosophy began to take wings, as it were, and fly off wherever it wished, without relationship to Scriptures. . . Aquinas had opened the way to an autonomous philosophy, and once the movement gained momentum, there was soon a flood.
Fifth, Aquinas, along with the other Schoolmen, developed the views of the sacraments which became the hallmark of Catholic theology by the time of the Reformation. Philip Schaff describes the methodology of the Schoolmen in devising their sacramental theories:
In defining what a sacrament is—quid est sacramentum—the Schoolmen started with Augustine’s definition that a sacrament is a visible sign of an invisible grace, but went beyond him in the degree of efficiency they ascribe to it. Beginning with Hugo, they assert in unmistakable language that the sacraments, or outward symbols, contain and confer grace—continere et conferre gratiam—the language afterwards used by the Council of Trent. They have a virtue in themselves.
In his Summa Theologica, Aquinas clearly stated his view that the sacraments perform their work through a virtue in themselves. He also stated unequivocally that the sacraments confer the new birth, justification, the grace of the Holy Spirit, sanctification, inward enlightenment, the washing away of guilt, and forgiveness of sins on every person who partakes of them. If you like the Federal Vision system, you will love Aquinas.
Sixth, Aquinas has some good things to say about theology proper, but he is wrong on every single point of soteriology. That is, the problem with Aquinas is precisely the same problem that Protestants have with the Catholic Church. Too many Reformed scholars are mesmerized by Aquinas’ clear assertion of unconditional election, but they fail to realize that later in his Summa Theologica he teaches that election can be nullified by the unfaithfulness of the elect.
Like Catholicism, Aquinas held that justification is the infusion of grace which, thereby, confuses justification with sanctification. Aquinas denied the certain perseverance of the saints and, thus, also denied that believers could be assured of their salvation. The closest he would come to assurance was in calling it the ‘hope of a wayfarer.’ Aquinas held to a union with Christ that could be lost. He defined apostasy as something that could be committed by a Christian without completely falling away from faith. He denied that the righteousness of Christ is imputed to believers. Rather, he taught that our own good works become our righteousness. Thus, his writings represent a different gospel than the one taught in Scripture. Heed the warning of the Apostle Paul in Galatians 1:8. The one who preaches any other gospel than the one taught in the Scripture is to be accursed.
For all these reasons and more, I would encourage people not to read Thomas Aquinas. If you do, read him the way you would read any other author whose system you knew contained poisonous, soul damning errors. There is value, perhaps, in scholars critically reading such works in order to warn others against their errors. Yet, most ministers and believers will profit more by reading the writings of safe guides such as the Reformers, the Puritans, and other great evangelical authors.
Dewey Roberts is a Minister in the Presbyterian Church in America and is pastor of Cornerstone Presbyterian Church in Destin, Fla. He is the author of Historic Christianity and the Federal Vision.
 Aeterni Patris, Encyclical of Pope Leo XIII, “On the Restoration of Christian Philosophy”, accessed at: http://w2.vatican.va/content/leo-xiii/en/encyclicals/documents/hf_l-xiii_enc_04081879_aeterni-patris.html on June 26, 2015.
 Francis A. Schaeffer, Escape from Reason (Downers Grove, Illinois: Intervarsity Press, 1968), 11-13.
 Philip Schaff, History of the Christian Church, Volume V: The Middle Ages (Grand Rapids, Michigan: Wm. B. Eerdmans Publishing Company, 1981), 704.