48. We have said that these things appear to be mere matters of faith. But the thought of the understanding derives its coming into manifest being [trahit suum existere] from the love of the will, which is the inmost being [qui est esse] of the thought in the understanding, as has been said above (n. 43). For whatever anyone wills from love, he wills to do, he wills to think, he wills to understand, and he wills to speak; or, what is the same, whatever anyone loves from the will, he loves to do, he loves to think, he loves to understand, and he loves to speak. To this is also to be added, that when a man shuns what is evil as a sin, he is in the Lord, as shown above, and the Lord then works everything. And therefore to those who asked Him what they should do that they might work the works of God, He said:
This is the work of God, that ye believe in Him whom He hath sent (John 6:28-29).
To "believe in the Lord" is not only to think that He is, but also to do His words, as He teaches elsewhere.