Angels: Raphael; Gabriel; Michael; Azrael/Sariel. Azrael the Angel of Death became conflated with the fallen angel Sariel in certain traditions such as Enochian mysticism. Sariel is also identified as a primordial Power and, in the apocryphal Book of Enoch, taught humans to interpret patterns in Nature such as regulating time. Intriguingly in 'The Fall', the Ancients credited themselves with facilitating human development towards its own demise, which ultimately proved to be a phyrric victory for the Ancients, in large part due to the rash acts of the Master.
The rending of Azrael, cf., Kabbalah: the shattering (shevirah) of primordial man, Adam Kadmon, who contained every soul who would ever be born on earth. Furthermore, the number of bodily features of Azrael traditionally corresponds to the number of souls upon the earth. Such symbolic potentials became literally represented in 'The Strain' story-verse as a boundless contagion contained within the Ancients and unleashed by the Master against all of humanity.
The Woodcarver (cf., the Carpenter)
Falling spacecraft described as "God's own fingernail" or "the finger of God" (cf., Yod); also, "[echoing] the comet that had announced the birthing site of another god walking the earth two thousand years ago" (q.v., the Carpenter)
Notion of Eph as marked or chosen: based on Roman dictum that whom the gods love they drive mad or die (young), and his monomania and unhinged mental state associated with the ersewhile condition of being fey. Also, in addition to Tragic Hero, the notion of Eph as Wounded Healer, single-mindedly driven towards catharsis (kenosis) and resolution.
Eph was able to satisfy the uncompromising will of higher powers through primal motivations such as emotions like love, hence he served as beacon in the quest to defeat the Master. Eph's lack of aptitude to carry out the plan was upheld by Fet in the role of custodian and his lack of prowess upheld by Gus as defender, thus both served as paladins rallying around the beacon despite the tensions within the fellowship. (These arrangements find parallels in Hinduism, where love or devotion is a spiritual resource that one can fall back on when aptitude/knowledge and prowess/deeds fail, as outlined in the Bhagavad Gita. Diminished spiritual competence is characteristic of the age of Kali Yuga and is also notably mirrored in the last of the four ages of Tolkien's Middle Earth, that of Men.)
Despite its supernatural backdrop, the emphasis of 'The Strain' saga lies with the psychological rather than the religious depiction it is popularly mistaken for. It explores how a secular mind like Eph would cope in an encounter with uncompromising higher powers at work in the modern world, where intervention or faith of a divine nature is not easily obtained. Although Eph may be considered chosen, it might also be tempting to regard him as a modern prophet. However, he does not share such religious motivations and is merely a naked instrument of divine will, despite experiencing traits like madness and reclusion common to many biblical prophets of old.
Towards the end of the saga, due to mental exhaustion and stress, Eph exhibits an altered state of consciousness loosely resembling the effects from ascetic practices similar to Indian sadhana or Native American vision quests.