Compare 1 Enoch 19:1 and Justin Martyr, Second Apology 5

"... In his first apology (ca. 155) Justin defends the Christians against, among other slanders, the charge of atheism. He accuses their detractors of not examining what they say and responding with passion under the guidance of evil demons ... Here Justin argues emphatically that Greek religion is demon-based - a theme which will emerge among other apologists for the faith. But who are these demons who through terror induced humans to call them gods? Justin answers this query in his second apology (circa 161). In it he explains that God entrusted the care of humanity and all things under heaven to angels ... Justin reproduces several aspects of the angel story - their lust, fatherhood, and teachings - but also their role in religion. However, in his version the demons are the offspring of the angels, not apparently the emanations from the giants dead bodies. Here, as in 1 Peter 3:19-20, the basis for Justin's claims is 1 Enoch 19:1. Justin's point is that the gods of Greek mythology, who committed a host of immoral deeds, were actually the evil demons depicted in the Enochic angel tale ..."