Prima facie this has a strong edge to it. But the truth is, the Church does not believe any fables; she believes and proclaims those truths conveyed by means of any fabulous cultural accommodation on God's part in His revelation within and through genuine human cultures. The "gospel fictions" concerning Jesus, far from "disproving" his existence or identity, actually situate and authenticate him as a vital member of the culture into which He was incarnated. That He resembles this or that figure in antiquity is a function partially of the sheer commonalities to be seen between remarkable careers of life, but more importantly of the skilled efforts by the Gospel authors to highlight the truth of Jesus in the words and pictures of their day. As much mileage as various critics like to get out this or that theory of "mythic redundancy" – a convergence, by the way, that often rests on much more superficial length than serious depth –, such similarities only go to explain even better what the authors were trying to say. More than that, insofar as far Jesus, a proper man of his proper milieu, was aware of the religious themes and tropes of his milieu, we see his intentional actions as "retracing" and a comprehensive redemption of those religious half-truths into the full truth that is His own Person. To see a link between Jesus' behavior in X and Hercules' behavior in Z, is but to hear the Gospel authors saying, "What you understand from Hercules here, is what Jesus was too… only more so, and in our common flesh and blood."
For our purposes vis a vis Frey, the point is that if he had consciously and rather more clearly "borrowed from" the mythology of addiction/recovery literature, he would be seen as a true heir to such literature. But since he attempted to fabricate new myths in idiosyncratic terms, he cut himself off from explaining himself in those pre-existent literary terms. The Gospel authors, wherever they truly (and not merely superficially) appear, to "borrow from" Greco-Roman literature, this they do as a formal technique of situating Jesus in his culture and enlivening His Person in the culturalized minds of the early Church. To consider the Gospel authors "adapting" Greco-roman literature for narrative purposes is little more shocking to me than the fundamental Christian claim that Jesus and the Apostles "adapted" the pre-existent Jewish narrative in the revelation of the Kingdom of Heaven. Being an orthodox Christian does not entail denying Jesus' Jewish roots any more than it entails denying His Greco-Roman cultural associations. Saying Jesus is "disproved" on account of pagan similarities -- which, I must reiterate, too often get a facile green light from eager skeptics – is as silly as saying He is disproved on account of Jewish similarities in the Gospels. The Gospels, and the Church with them, say, "Yes, Jesus is many of those things... but so much more. Yes, we see 'pre-echoes' of the Gospel outside the Gospels... but we insist on heeding the Word made flesh in favor of those passing echoes of the Word."
The Incarnation claims that Christ the Logos, true God, became Jesus the Messiah, a true man; and being a true man means having a real culture. The Incarnation is therefore no less a biological "enfleshment" of God into a human than it is a cultural "enfleshment" of the Revelation into a human milieu, and vice versa. To deny that the Incarnation, so to speak, absorbed within itself distinct cultural aspects of the time is a sort of supra-Nestorianism, resting on the Nestorian heresy that the human aspect of Jesus was and is swallowed up in or erased by the true Christ, the divine Logos. The truly Christian understanding of the Incarnation is not so pallid; we believe in Jesus Christ, a man of His age, of His place, of His culture and of His surrounding literature.
From this radical, and not weakly Nestorian, enfleshment of God-as-man, we can and must embrace the full absorption of humanity into the Godhead. The Resurrection and Ascension of Christ are the signs that this radical and "singular" enfleshment is no longer singularly "trapped" within its primal biological and cultural conditions. Further, the ongoing presence of the Holy Spirit in the Church is the sign that the Incarnation is no longer confined to this or that, or even our favorite few, ages and places of Christianity. In much the same way the Holy Spirit enables Jesus to be appropriated by all peoples, yet without being eviscerated as the individual man He truly was, so too the Gospel authors could appropriate Jesus into His original milieu.