The Essenes, a group of zealot Jews who separated themselves from what they perceived to be an apostate Jewish society, became very attached to the personal Satan myth. They had a bunker mentality, critical of and feeling persecuted by Jewish society as a whole, and bitterly resentful of the nation's domination by pagan Romans. They developed the ideas of the Book of Enoch in their Damascus Covenant and later in their Rule Of The Community and War Scroll. They felt that all their "moments of tribulation are due to this being's hostility [i.e. mastema, the Satan figure]. all of the spirits that attend upon him are bent on causing the sons of light [i.e. themselves] to stumble" (2). Thus they demonized all their opponents as somehow in league with Satan, thereby justifying them in preparing to violently and heroically fight the Romans with the belief that God was on their side. Tragically they failed to realize that their theology on this point was shaped and influenced by the pagan dualistic ideas which in other contexts they so vehemently criticized. They condemned the rabbis for claiming [correctly, and in line with Bible teaching] that there were only two tendencies in man, to evil [the yetser-hara] and to good [the yetser-tob]. Sadly they missed the point- that life before God is all about controlling the evil tendency and developing the good; and thus they minimized the need for personal spirituality, externalizing it all into caustic language and literal warfare against their enemies. As an aside, it's noteworthy that Yigael Yadin, an Israeli Defence Force General and also an archaeologist and academic, edited the War Scroll and used it as justification for Israel's 20th century conflicts with the Arabs (3).
It's been pointed out and exemplified beyond cavil that Paul uses much Essene terminology (4). I suggest he does this in order to deconstruct it. When he urges the Roman Jews to "cast off the works of darkness and put on the armour of light" (Rom. 13:12), calling his converts "the children of the light and children of the day" (1 Thess. 5:5), Paul is alluding to the Essene ideas. But he's saying that the children of light are to wage spiritual warfare against themselves, their own hearts, quit the things and habits of the flesh etc.- rather than charge off into literal battle with physical armour against the Romans. Likewise when Paul insists that God hardened Pharaoh's heart (Rom. 9:14-18), he is not only repeating the Biblical record (Ex. 9:12,16; 33:19), but he is alluding to the way that the Jewish Book of Jubilees claimed that Mastema [the personal Satan] and not God hardened Pharaoh's heart.
Likewise John's Gospel is full of reference to Essence concepts. It's been widely argued that John's language alludes to the threat of incipient Gnosticism, and this may be true. But it's likely that John was written quite early, even before AD70 (5). In this case, when John speaks of light and darkness, children of light and darkness, the Jewish 'Satan' / adversary to Christianity as "the ruler of this world" [see section 2-4], he would also be alluding to these common Essene ideas. For John, following the light means following Jesus as Lord; the darkness refers to the flesh, the desires within us to conform to the surrounding world and its thinking. His point, therefore, is that instead of fantasizing about some cosmic battle going on, true Christians are to understand that the essential struggle is within the mind of each of us.