Titus 1:4

Natural generation does not operate by the assent of the one who is born, whereas the birth that comes from faith requires such assent. Although the one who preaches may sincerely believe, he who hears, unless he takes to himself what he learns with faith, cannot be called the son of the preacher.

to Titus, my true child in a common faith: Grace, mercy, and peace from God the Father and Christ Jesus our Savior. to Titus, my true child. For one is a child because they have been baptized by them, but not legitimately, because they are sinful. The reason for you being my child, Paul says, is shared faith. He praises Titus as having nothing more than faith in him. Another way. Titus, the child of Paul, as he was taught faith by him, and according to common faith, that is, from baptism, is a brother of Paul. For there is one Father, Christ, and one mother, the baptismal font. Grace, mercy. It is fitting that grace and mercy be prayed for Titus, who is a teacher. For if you do not govern the people, that is, with grace, mercy, and peace, Paul says, the ship of the Church will be overturned. On the training of teachers for ministry and the rebuke of the disobedient.

And the Apostle writes to his beloved son Titus, which is called in Greek, γνησίῳ τέκνῳ: and cannot be explained in Latin: for γνήσιος means this rather, when someone is called faithful and proper, and (so to speak) legitimate or genuine without comparison to another. From which we understand that there was much difference even among the sons of Paul, that he had some γνησίους, that is, most genuine, closely connected to himself, and born of true marriage and free procreation; but others almost from a handmaid and from Hagar, who cannot receive inheritance with the free son, Isaac. For the speech and wisdom and doctrine by which Titus instructed the Churches of Christ, made him a true son of the Apostle, and separate from all the companionship of others. Let us see after this what follows: According to the common faith, whether he said that it was common to all who believed in Christ, or common to him and Titus alone. Indeed, to me it seems that the common faith of the Apostle Paul and Titus was better than that of all believers; among whom, due to the variety of opinions, faith could not be common but diverse. Finally, the preface of the Epistle and the greeting of the Apostle's preface to Titus are completed with such an ending: Grace and peace from God the Father and Christ Jesus our Savior. Whether both grace and peace are given to both the Father and Christ Jesus, and both can be understood from each other, or whether grace refers to the Father and peace to the Son, must not be passed over without doubt. The Apostle had cursed some, that grace and peace would multiply to them: now, to Titus, peace and grace are placed without multiplication. Noah the righteous man, and the only one saved in a storm-tossed world, is said to have found not many graces, but one grace before God. And Moses said to the Lord, "If I have found grace with you" (Exodus 33:13). And wherever grace is placed in the person of the saints, seek and you shall find it, not that they have found graces but grace. That merchant of the Gospel who had many pearls, at last found one precious one, which he bought alone from many pearls (Matthew 13). For the perfect, indeed, it is to buy one pearl and one treasure for all pearls and all their substance by their business: but for those who are just beginning and are still on the way, not only one and alone but many pearls must be had.