Between the years 50 – 280 AD, the early Christian church reeled under external and internal conflicts. Judaism and Paganism despised the Christians, and the Gnostics and Montanists infiltrated the ranks of polite Christians and surreptitiously unraveled their confidence in the recently ascended Messiah, Jesus Christ. Of these four groups just mentioned (Jews, Pagans, Gnostics, and Montanists), this paper will seek to explore the third; that is, the Gnostics, limning their common doctrines, highlighting their effects on the early church, and then, finally, terminating with Irenaeus' response to the Gnostics.
Toward an Understanding of the Gnostics
To suggest that Gnosticism was simply a particular, or peculiar look at Christian doctrine, or a natural outgrowth of Hellenistic philosophy intermingling with the New Testament documents would be to fly in the face of historical witnesses and opponents to Gnosticism. One would also do a grievous misdeed to reduce the phenomenon of Gnosticism to a uniform collection of heretical writings. Gnosticism pre-existed the New Testament writings, having its first forms in "Jewish, pagan, and Oriental sources." It thereby preceded its early church opponents, such as Ignatius of Antioch, and Irenaeus bishop of Lyons. Moreover, Gnosticism within its own ranks calculates heterogenous beginnings, and accordingly, divergent and sometimes conflicting teachings. All that being said, it would be appropriate to take a cursory look at the origins of Gnosticism before moving on to characteristics of Gnosticism, its impact on the early Christian church, and the views of its opponents; in particular, Irenaeus bishop of Lyons.
As noted above, Gnosticism – which comes to us from the Greek word γνώσις (gnosis), meaning "knowledge" – does not have one genus, or one traceable root. What can be said of its beginnings is that "it is only by inference that we can argue that there is a pre-Christian gnosis." Early church fathers attribute the first Gnostic heresy to Simon Magus of Acts 8:9-24, and their assertions should be taken with all seriousness. So if by inference a pre-Christian gnosis can be suggested, then by the same measure it would not be inappropriate to maintain that Simon Magus was influenced by an already extant Gnostic influence in his time. Furthermore, it is debatable that Simon Magus' gnosis was coterminous with early Christianity since the New Testament witness includes him at the time of St. Peter's ministry, not long after Christ's resurrection and ascension. The early church fathers then, have a debatable point of which there is no clear, or definitive resolution.
Nevertheless, in "the opinions of various scholars, Gnosticism arose out of (1) Hellenistic philosophy, (2) oriental religion, chiefly Iranian, (3) Christianity, or (4) heterodox Judaism." Other historians conjecture a fifth possibility: Gnosticism was an existential reaction to the socio-political pressures of the early first centuries.
...the political apathy and cultural stagnation of the Eastern empire in the first two centuries of this era coincided with the influx of Oriental religion into Hellenistic culture... many people at the time felt profoundly alienated from the world in which they lived and longed for a miraculous salvation as an escape from the constraints of political and social existence.Be that as it may, it is historically clear, and well maintained that for "all practical purposes the Gnostics must have been ex-Jews, renegades from their religion, for they had abandoned the deity of the Creator, the binding character of the law of Moses, and the doctrine of the resurrection." In all cases, the Gnostics drew on the Oriental emphasis of "absolute dualism between God and the world," body and soul, and from Greek neo-Platonic notions of intermediary beings communicating between God and man so as not to allow for a breach in the sanctity of God's total transcendence.
So if Gnosticism's origins are unclear, or highly speculative, it would not be inappropriate at this point to move into the area of what we can know; namely, what Gnosticism is, for this will aid in understanding its critical effects on the early Christian church. Furthermore, an understanding of what Gnosticism is will reinforce why it "threatened [the church's] spiritual foundation and its religious character," and why such historical figures as Ireneaus of Lyons fought so diligently against it.
 Quasten, Johannes Patrology v.I (Allen, TX: Christian Classics, 1983) 254.
 Kelly, J.N.D., Early Christian Doctrine Rev. ed. (New York: HarperCollins Publishers, 1960) 23.
 McKechnie, Paul, The First Christian Centuries (Downer’s Grove, Illinois: Intervarsity Press, 2001) 101.
 Grant, R.M., Gnosticism and Early Christianity (New York: Columbia University Press, 1959) 6-7.
 Grant, R.M., 13
 Ibid., 13
 Pagels, Elaine, The Gnostic Gospels (New York: Vintage Books Edition, 1981) xxxii - xxxiii
 Ibid. xxxii
 Grant, R.M., 26
 Quasten, Johannes, 254
 Ibid. 255
 Ibid. 254
(Category: The Church: Christian History)