Chapter 4 — Part I — Article II (Of the Son of God)
Section 139. Q. Why is Jesus Christ called the Son of God, Only-begotten? A. By this is signified that he only is the Son of God begotten of the substance of God the Father; and so is of one substance with the Father; and consequently excels, beyond comparison, all holy angels and holy men, who are called sons of God by grace. John i. 12.