The rational demonstration of God by the existence of the world
St. Augustine and St. Thomas speak about the rational demonstration of the existence of God. St. Augustine affirms in his discourse about the existence of immaterial truths: "invisible perfections are made visible to the intelligence by the consideration of the creatures" (Book VII, C XX, Book Confessions).
Thomas Aquinas in his book Sum of Theology takes a quote from the epistle to the Romans: "The invisible of God has become perceptible through the knowledge of the created" 1 Rom 20 (Q 79 A9, Summa Teologiae). In the books of the Psalms there is a similar affirmation: "the heavens declare the Glory of God and the firmament proclaims the work of his hands", Psalm 19: 2.
According to the scholastics, good and wisdom are substances and are identified with God. God is wisdom itself.
Although we can infer the existence of uncreated, eternal and immaterial entities (entelechies), in this case the good, the wisdom and God, for the existence of the world, for the theologians the demonstration of God is not a rational process, it can not be through reason that we reach the knowledge of ultimate truths, the limit of human reason is prudence, this is one of the most important conclusions of St. Augustine in his book Confessions, remember the statement of Jesus: "this is eternal life that they may know you, the only true God ", John 17: 3.
Therefore, an effort of conversion is needed to reach the infused virtue of Charity, that is, the state of enlightenment, and with it the Gift of Knowledge and so obtain the ultimate knowledge of the truth and God. It could be said from the scholastics that the need for logical proofs about the existence of God is due to the perceptive insufficiency of man, thence the myth of Plato's cave.