Chapter 4 — Part I: The Creed — Article II: And in Jesus Christ, His Only Son, Our Lord
Section 21. While we thus acknowledge His twofold Nativity; we believe Him to be one Son, because His divine and human natures meet in one Person. As to His divine generation He has no brethren or coheirs, being the Only-begotten Son of the Father, while we mortals are the work of His hands. But if we consider His birth as man, He not only calls many by the name of brethren, but treats them as such, since He admits them to share with Him the glory of His paternal inheritance. They are those who by faith have received Christ the Lord, and who really, and by works of charity, show forth the faith which they profess in words. Hence the Apostle calls Christ, the first-born amongst many brethren.