9 The First Vatican Council teaches, then, that the truth attained by philosophy and the truth of Revelation are neither identical nor mutually exclusive: “There exists a twofold order of knowledge, distinct not only as regards their source, but also as regards their object. With regard to the source, because we know in one by natural reason, in the other by divine faith. With regard to the object, because besides those things which natural reason can attain, there are proposed for our belief mysteries hidden in God which, unless they are divinely revealed, cannot be known”. Based upon God's testimony and enjoying the supernatural assistance of grace, faith is of an order other than philosophical knowledge which depends upon sense perception and experience and which advances by the light of the intellect alone. Philosophy and the sciences function within the order of natural reason; while faith, enlightened and guided by the Spirit, recognizes in the message of salvation the “fullness of grace and truth” (cf. Jn 1:14) which God has willed to reveal in history and definitively through his Son, Jesus Christ (cf. 1 Jn 5:9; Jn 5:31-32).
Source: Fides et Ratio (Vatican.va)