Despite their radical opposition, the Theologism and the Rationalism of the thirteenth century had at least one common feature; their onesidedness.
Theologism would maintain that every part of Revelation should be understood, while
Rationalism would uphold the view that no part of Revelation can be understood.
The historical significance of Saint Thomas Aquinas rests with the fact that he was the first medieval thinker to go to the root of the difficulty...
...[I]t was a problem of order...[I]n philosophy, where there is but one conceivable proper place for any given thing.
If...we learn from medieval theologians what is faith in an objective truth and what is an objective philosophical knowledge, we shall find ourselves possessed of both a Revelation and a Reason. There then will be something to harmonize, and anyone attempting to do it will end at last in meeting the real problem. But he can scarcely avoid meeting Saint Thomas Aquinas.
Reason and Revelation in the Middle Ages, Etienne Gilson
Theology and philosophy...form a strange pair of twins, in which neither of the two can be totally separated from the other, and yet each must preserve its own task and its own identity. It is the historical merit of Saint Thomas Aquinas – in the face of the rather different answer offered by the Fathers, owing to their historical context – to have highlighted the autonomy of philosophy, and with it the laws and the responsibility proper to reason, which enquires on the basis of its own dynamic
...Saint Thomas’s idea concerning the relationship between philosophy and theology could be expressed using the formula that the Council of Chalcedon adopted for Christology: philosophy and theology must be interrelated “without confusion and without separation”. “Without confusion” means that each of the two must preserve its own identity. Philosophy must truly remain a quest conducted by reason with freedom and responsibility; it must recognize its limits and likewise its greatness and immensity.
Theology must continue to draw upon a treasury of knowledge that it did not invent, that always surpasses it, the depths of which can never be fully plumbed through reflection, and which for that reason constantly gives rise to new thinking. Balancing “without confusion”, there is always “without separation”: philosophy does not start again from zero with every thinking subject in total isolation, but takes its place within the great dialogue of historical wisdom, which it continually accepts and develops in a manner both critical and docile. It must not exclude what religions, and the Christian faith in particular, have received and have given to humanity as signposts for the journey.
Various things said by theologians in the course of history, or even adopted in practice by ecclesiastical authorities, have been shown by history to be false, and today make us feel ashamed. Yet at the same time it has to be acknowledged that the history of the saints, the history of the humanism that has grown out of the Christian faith, demonstrates the truth of this faith in its essential nucleus, thereby giving it a claim upon public reason.
Of course, much of the content of theology and faith can only be appropriated within the context of faith, and therefore cannot be demanded of those to whom this faith remains inaccessible. Yet at the same time it is true that the message of the Christian faith is never solely a “comprehensive religious doctrine” in Rawls’ sense, but is a purifying force for reason, helping it to be more fully itself. On the basis of its origin, the Christian message should always be an encouragement towards truth, and thus a force against the pressure exerted by power and interests.