[I]t is impossible that one and the same thing should be believed and seen by the same person. Hence it is equally impossible for one and the same thing to be an object of science and of belief for the same person. It may happen, however, that a thing which is an object of vision or science for one, is believed by another: since we hope to see some day what we now believe about the Trinity, according to 1 Corinthians 13:12: "We see now through a glass in a dark manner; but then face to face": which vision the angels possess already; so that what we believe, they see. On like manner it may happen that what is an object of vision or scientific knowledge for one man, even in the state of a wayfarer, is, for another man, an object of faith, because he does not know it by demonstration. Nevertheless that which is proposed to be believed equally by all, is equally unknown by all as an object of science: such are the things which are of faith simply. Consequently faith and science are not about the same things.This does not, however, deny that "God's existence is not merely an object of natural rational knowledge, but also an object of supernatural faith (De fide)" because
As ground for [it being "impossible for the same truth to be known and believed by the same person": impossible [...], quod ab eodem idem sit scitum et creditum (S. th. 2 II, 1, 5),] [St. Thomas] submits that the clear insight into the truth associated with knowledge cannot co-exist with the obscurity of faith. It is, however, possible, that the same truth could be known by one person and believed by another. According to the teaching of St. Thomas, it is also possible for the same person at the one time to have a natural knowledge of the existence of God as the originator of the natural order, and a supernatural faith in the existence of God as the originator of the supernatural order, because the supernatural faith comprehends truths which are not contained in natural knowledge (difference of material object).Yet faith is not obscure; the Christian faith "so quickens the human mind that without difficulty it pierces the heavens, and, illumined with divine light, contemplates first, the eternal source of light, and in its radiance all created things" (Trent Catechism) and it "is a kind of knowledge, inasmuch as the intellect is determined by faith to some knowable object" (Summa Theologica Iª q. 12 a. 13 ad 3). Possibly because of this, St. Albertus Magnus, St. Thomas's teacher, believed that it is indeed possible "for the same truth to be known and believed by the same person." But why does knowledge of God, regardless of how one obtains it, even matter with regard to the physical sciences? The reason is that God is the cause of the physical world, and one can know effects by their causes and vice versa (cf. Rom. 1:20 and 1 Cor. 2:10).
—Dr. Ludwig Ott's Fundamentals of Catholic Dogma pg. 17
Even though humans are finite beings, we have immaterial, intellectual souls, viz., intellects or minds. Human souls animate the human body, and, unlike animals' souls, still exist after the death of the body because they do not depend on matter for their existence. That human souls are eternal we prove as follows: Because a knowing power, e.g. the eye, contains the form of the the thing known, color; similarly, the human intellectual soul—the self-subsisting, eternal, God-created form of a human being's material body—is also a knowing power. The things it knows are universal concepts, unique to humans. We, unlike animals, can abstract from particular sense-knowledge, e.g. "this bird," to the universal concept of "bird." Because universal concepts are immaterial, so too must our souls be because universal concepts are proper to them. St. Thomas explains it thus:
[W]e may proceed from the specific notion of the human soul inasmuch as it is intellectual. For it is clear that whatever is received into something is received according to the condition of the recipient. Now a thing is known in as far as its form is in the knower. But the intellectual soul knows a thing in its nature absolutely: for instance, it knows a stone absolutely as a stone; and therefore the form of a stone absolutely, as to its proper formal idea, is in the intellectual soul. Therefore the intellectual soul itself is an absolute form, and not something composed of matter and form. For if the intellectual soul were composed of matter and form, the forms of things would be received into it as individuals, and so it would only know the individual: just as it happens with the sensitive powers which receive forms in a corporeal organ; since matter is the principle by which forms are individualized. It follows, therefore, that the intellectual soul, and every intellectual substance which has knowledge of forms absolutely, is exempt from composition of matter and form.Therefore, the mind does not depend on an organ like the brain; the brain, along with the other sense organs, informs the soul because all knowledge originates in the senses. Since the human intellect is capable of knowing so many great universal concepts and because the soul is not divided—e.g., into a soul or power of the soul for subjective knowledge, scientific knowledge, faith knowledge, etc.—it behooves empiriological scientists to combine the various modes of knowledge—philosophy, science, faith, and reason—to arrive at a more accurate, truer knowledge of reality. With God's grace, which builds on man's finitude and human nature, humans can indeed reach truly amazing intellectual heights, perhaps even devise a "theory of everything" in a new, paradigm-shifting physics.