4. The occasion for writing is set forth from Luke 1:1-3.
The occasion, which Luke had for writing the Gospel, he himself makes known at the beginning in these words:Ἐπειδήπερ πολλοὶ ἐπεχείρησαν ἀνατάξασθαι διήγησιν περὶ τῶν πεπληροφορημένων ἐν ἡμῖν πραγμάτων,καθὼς παρέδοσαν ἡμῖν οἱ ἀπ᾽ ἀρχῆς αὐτόπται καὶ ὑπηρέται γενόμενοι τοῦ λόγου·ἔδοξε κἀμοί, παρηκολουθηκότι ἄνωθεν πᾶσιν ἀκριβῶς, καθεξῆς σοι γράψαι, κράτιστε Θεόφιλε, Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us, even as they delivered them unto us, which from the beginning were eyewitnesses, and ministers of the matter; it seemed good to me also, having had perfect understanding of all things from above, to write unto thee in order, most excellent Theophilus. Therefore, the many authors provided for him the occasion for writing; not indeed those enemies of the truth that with malice and hatred of the truth, so that they might establish their heresies, placed their Gospels under the names of Apostle, as some think, since Luke would not have so lightly glanced over a wicked and noxious fraud of this sort:nor, as Beza, Gomarus, and other think, imprudent patrons of the truth, who, moved prematurely and in ignorant zeal to propagate the truth of the Gospel, and destitute of the inspiration of the Holy Spirit, concocted and published uncertain narratives concerning Christ:but rather the θεόπνευστοι/inspired authors, Matthew, Mark, Paul; who of things altogether certain wove together narration by the Divine Spirit, and according to the tradition of those that were from the beginning eyewitnesses and minsters of the events.Luke, following the example of these, thought to himself that those things that the Spirit of God suggested to him were also to be consigned to writing, so that from the writings of more men greater ἀσφάλεια/certainty and security might shine forth to the faithful.For, that the same things were written by many, it is important to the Church for the confirmation of the faith.
 Luke 1:4: “That thou mightest know the certainty (τὴν ἀσφάλειαν) of those things, wherein thou hast been instructed.”