Tertullian Against Marcion Book V ,"[121] Tertullian On Monogamy For if" faith" is the source whence we are reckoned to Abraham as his "sons" (as the apostle teaches, saying to the Galatians, "You know, consequently, that (they) who are of faith, these are sons of Abraham"[32] (nations) who, as the fruit of the "faith" which precedes digamy, had to be accounted "sons of Abraham."[36]