1. The inscription of the book. Why do the books setting forth the history concerning Christ go by the title of Gospels? The twofold notion of Gospel: ὑπομνημονεύματα/commentaries/registers.
This first book of the New Testament is inscribed τὸ κατὰ Ματθαῖον Εὐαγγέλιον, the Gospel according to Matthew. Namely, because Saint Mark made the title of the history concerning Christ, consigned to writing by himself, the Εὐαγγελίου/Gospel, Mark 1:1, it was pleasing to the Church from the times of the Holy Apostles to inscribe those four books in which the history of the life and death of Christ is comprehended with the title of Gospel, even as Justintestifies in his Apologia, and, I add, as it is done by the Translators, Latin, Syrian, and Arabian. Which term, although it properly signifies a joyful announcement, in Theology is used in two ways. For it denotes both the doctrine concerning salvation through faith in Christ, absolutely, whether to be exhibited more broadly, Hebrews 4:2, or having been exhibited more narrowly, Matthew 4:23; 9:35; 24:14; Mark 1:14; 14:9; Luke 2:10; Romans 1:1-3, by a Synecdoche of genus for species; and the four books, in which the history of the life and death of Christ is delivered, κατ᾽ ἐξοχὴν, pre-eminently, and comparatively, that is, if they be compared with the other books of the New Testament, not concealing the coming of Christ to be sure, yet passing by the history of the sayings, actions, and sufferings of Christ, and generally intent on the explanation of doctrines. That is, just as the five books of Moses are regarded as the foundation of the Old Testament, and the first perfect canon of the faith given by God, in the explanation of which the writings of the Prophets thereafter serve; so in a similar manner the four Gospels underlie the other books of the New Testament, after the likeness of a perfect canon of faith and manners, and excel them in the perfection of the complete work. For they fully explain the sentence of the law, the articles of faith, the institution of the Sacraments and discipline of the Church, and the Lord’s prayer. And with good reason the ancient Christians also inscribed these books or ὑπομνημονεύματα, as Cyrilcalls them, that is, Commentaries/Registers of the matters conducted by Christ, as Εὐαγγέλιον/Gospel, so that by that name also the reader might be advised how much more joyful the matters these books contain, than the oracles of the Prophets, most of which sadly displayed that title מַשָּׂא/burden.
Justin, also known as the Martyr, was one of the great Greek apologists of the second century. Cyril of Alexandria (c. 378-444) was a participant in the third ecumenical council, held at Ephesus. He repudiated the heretical Nestorian Christology but tended himself to the monophysitism. See, for example, Isaiah 13:1; 15:1; Nahum 1:1; Habakkuk 1:1.