From Pope St. John Paul II’s encyclical Fides et Ratio (1984):
With regard to the intellectus fidei, a prime consideration must be that divine Truth “proposed to us in the Sacred Scriptures and rightly interpreted by the Church’s teaching”89 enjoys an innate intelligibility, so logically consistent that it stands as an authentic body of knowledge. The intellectus fidei expounds this truth, not only in grasping the logical and conceptual structure of the propositions in which the Church’s teaching is framed, but also, indeed primarily, in bringing to light the salvific meaning of these propositions for the individual and for humanity. From the sum of these propositions, the believer comes to know the history of salvation, which culminates in the person of Jesus Christ and in his Paschal Mystery. Believers then share in this mystery by their assent of faith.
For its part, dogmatic theology must be able to articulate the universal meaning of the mystery of the One and Triune God and of the economy of salvation, both as a narrative and, above all, in the form of argument. It must do so, in other words, through concepts formulated in a critical and universally communicable way. Without philosophy’s contribution, it would in fact be impossible to discuss theological issues such as, for example, the use of language to speak about God, the personal relations within the Trinity, God’s creative activity in the world, the relationship between God and man, or Christ’s identity as true God and true man. This is no less true of the different themes of moral theology, which employ concepts such as the moral law, conscience, freedom, personal responsibility and guilt, which are in part defined by philosophical ethics.
It is necessary therefore that the mind of the believer acquire a natural, consistent and true knowledge of created realities—the world and man himself—which are also the object of divine Revelation. Still more, reason must be able to articulate this knowledge in concept and argument. Speculative dogmatic theology thus presupposes and implies a philosophy of the human being, the world and, more radically, of being, which has objective truth as its foundation.
89 Saint Thomas Aquinas, Summa Theologiæ, II-II, 5, 3 ad 2.
— Fides et Ratio 66