As stated previously, Aquinas did not believe that the theological virtues of faith, hope, and charity were means between two extremes, unlike the moral virtues. While the moral virtue of courage could be exercised in an extreme way as reckless behavior, the theological virtue of faith was more virtuous the more it was habituated. In other words, it is not possible to have too much faith in God.
The virtue of faith "perfects the intellect." Faith is a virtue "because it is a habit of the mind." Faith is what allows us to assent to what is unseen. Yet, one misunderstands Aquinas if faith is interpreted in fideistic fashion, that is as something that is opposed to reason. For Aquinas faith and reason are not synonymous, to be sure, but they, nevertheless, work hand in hand. Indeed, for faith to be the theological virtue that perfects the intellect it has to be concerned with what makes sense. In one sense, faith believes what is unseen precisely because of what is seen and experienced, that is, what is known in this existence. But faith moves beyond this existence to encounter ultimate questions of why human beings exists asking questions that concern the purpose of the entire universe itself.
And yet caution is necessary, for to state the connection between faith and reason in this way can lead to serious misunderstandings of Aquinas as well if he is read superficially, particularly when it comes to faith in God. For Aquinas, the notion of mystery is not what the theologian falls back on when the discussion of God has been exhausted in human terms; rather mystery is what the theologian starts with before the deliberations over God's person and nature begin. Thus mystery is not employed once there is nothing else to say, but mystery provides the context as the finite attempts to understand the infinite. Such an approach to the discussion of God assists in safeguarding against the human tendency toward idolatry in theological discussion. To affirm mystery is to acknowledge that God is indeed God and human beings are not.
The virtue of faith makes it possible to embrace the large picture of human existence and believe in God in spite of the truth that there is so much men and women do not know, are uncertain of, and in fact doubt. What we do not know means that faith cannot be reduced to what is rational, but faith cannot be exercised without the rational. Without faith, reason can find no ultimate answers; without reason, faith is intellectual suicide. Faith does not ignore scientific knowledge, and indeed incorporates it in the habituation of one's moral living; but only faith can make ultimate sense of what we know of the world and the universe, as faith asks the ultimate questions of existence and purpose... as it asks the ultimate question of God.
Thus faith displays more than knowledge. It manifests wisdom. Such wisdom is not stagnant; it grows and develops and changes in the believer over time as he or she continues to search what is embraced by faith while many questions remain unanswered.
The theological virtue of faith precedes the theological virtue of hope; for without faith in God, one cannot hope in God.