After treating the many points of doctrine in the works of Thomas, we will here confine ourselves to consider who he was: a theologian and a christian philosopher. He knew how to organize knowledge under faith and to organize the culture of his time in accord with and for the service of christian faith. His work of inculturating the faith was one of the great medieval intellectual contributions. He understood that the age of authority and tradition was being replaced by a new age of science and reason. At the same time his contribution does not fall into a supernatural fideism nor into a radical naturalism.

His work came about with the decisive help of Aristotelian philosophy. Thomas was the first to introduce the philosophy of Aristotle into the work of theology, indeed for the service of theology. He saw that theology was the science of a faith that needed to understand the deeds and words that make up that faith. His choice scandalized not only the theologians of the Augustinian school of this time, but also many later theological schools that even today frequently accuse him of having contaminated christian faith with Greek thought.

Thomas was able to build a synthesis between the two fonts of human knowledge that for ages had been in opposition: rational philosophy and revelation or theology. He did this by reconciling christian faith with human intelligence, that is by refuting the extremists of the Platonic-Augustinian schools or the Aristotelian-Averroist schools.

This was possible thanks to his utilization of not only the works and the thought of Aristotle, but also the works of the Fathers, and the theology of his contemporaries. He did not completely refute the latter, nor did he interpret the Fathers by simply repeating what they had said.

It is well known that Thomas, who cites with great frequency the Church Fathers, be they Latin, particularly Augustine, or Greek (like the theologians before him), also frequently utilizes the thought of other non-christian authors: for example, the Arabs (Avicenna, Averroes, etc.) and the Hebrews (Ibn Gabirol, Maimonides, etc.) The result of this was to place the scientific contribution of these authors in line with the biblical wisdom and theological doctrine of the Church. This was done for a simple and most profound reason; namely, that truth, be it philosophical or of the faith, is one because its origin is in God.

Thomas also manifests a strong appreciation for the power of scientific reasoning in a confrontation with faith and he gave life to a new synthesis of faith and reason, demonstrating that the truths of theology and those of science are fully compatible, complementary, and not in conflict. This does not take away from the fact that some truths of faith (the mysteries of faith as the Incarnation and the Trinity) can be known only by divine revelation. It is not possible to demonstrate them, although it is possible to demonstrate that they are not logically contradictory. It is also true that the truths of reason, for example the scientific knowledge of reality, have a legitimate autonomy in which the faith has no competence. Examples are: the existence of god (the well known five ways), the immortality of the soul, etc. All these can be derived from natural reason and constitute the preambula fidei.

When he speaks of how we know things, Thomas abandons the old Platonic explanation in order to opt for a knowledge that is very active, intellectual, and capable of abstraction. Concepts and human language can be used, through the mediation of analogy, to speak even about the divine nature. There is the possibility of knowing the transcendent divine existence, but distinguishing that knowledge from knowledge of the esse of man. He does this while preserving the conviction that human nature alone cannot reach the divine essence. He places the two existences in an analogical relationship; that is to say he rigorously excludes that they are identical but also excludes that they are equivocal.

The anthropology of Thomas refutes the separatism or dualism between the soul and the body in order to recover the fundamental unity of man,