What is Postmillennialism?
A helpful definition of Postmillennialism has been offered by Dr. Kenneth Gentry. He writes:
Postmillennialism is the view that Christ will return to the earth after the Spirit-blessed Gospel has had overwhelming success in bringing the world to the adoption of Christianity.
I would like to focus on eschatology throughout Church History. Next Sunday, we will look at the Biblical Case for Postmillennialism and we will conclude our study answering objections to Postmillennialism and offering the practical implications of this position.
The Eschatology of the Early Church
The early church does not have a robust understanding of the doctrine of eschatology. In fact, when you read the early church fathers like Clement of Rome or Barnabas of Alexandria, one does not get the impression that millennial questions were on their mind. One thing we are sure from the Early Apostolic Church is that they believed that “Christ would return visibly in glory and that the dead would be resurrected for judgment.”
On the other hand, there is no general consensus on the question of when will Christ come again. Is it before the millennium or after? The early church did not have a systematic theology informing them what St. Paul believed about eschatology. However, one patristic father that made his millennial position clear is Papias. Through some of the fragments of his writings, we can reach the certain conclusion that Papias held to a form of Premillenialism. This is what we would call today Historical Pre-Millenialism or post-tribulationism. In other words, Papias believed that Christ’s Second Coming would occur at the end of the seven year Tribulation. Eusebius–who is often referred to as the Father of Church History–wrote in his Ecclesiastical History in the fourth century that Papias’ version of millenarianism was “bizarre.” (Ecclesiastical History, 3.39.11)
How about the second and third century apologists? What did they think about the millennium? There were many who dealt with millennium questions, but J.N.D. Kelly summarizes their understanding of the millennium in the following manner: “(these doctrines)…were held together in a naïve, unreflective fashion with little or no attempt to work out their implications or solve the problems that they raise.”
In essence, what you have is a maturing church in the early church learning and growing in their understanding of the millennium. You will find, however, a more mature explanation of the millennium question in the Nicene and Post-Nicene Fathers. For instance, in Athanasius you begin to find a note of optimism in the future of the world. In his book On the Incarnation you get a glimpse of his faith in the victory of Christ’s gospel:
Since the Savior’s Advent in our midst, not only does idolatry no longer increase, but it is getting less and gradually ceasing to be…while idolatry and everything else that opposes the faith of Christ is daily dwindling and weakening and falling, see, the Savior’s teaching is increasing everywhere!
So also, now that the Divine epiphany of the Word of God has taken place, the darkness of idols prevails no more, and all parts of the world in every direction are enlightened by His teaching.
There is in Athanasius a glimpse of what later would be called Postmillennialism. Athanasius believed that Christ will return again only after a lengthy period of time on earth of great peace and prosperity and where the influence of the gospel is known in every land. This is the reason the late David Chilton called Athanasius “the patron saint of postmillennialism.”
And one final note on St. Augustine. It is impossible to discuss eschatology without talking about Augustine. Everyone wants to claim Augustine as an apologist for their position. What exactly did Augustine believe about the millennium? Augustine’s position on the future of the world has its clearest expression in his classic work The City of God. One of the central themes of that book is the relationship between the city of God and the city of man or the secular city. Papias was one of the first to express a Premillennial view of the End Times. Augustine at one time held to a similar position, but later on in his life he strongly rejected it. He adopted a more symbolic understanding of Revelation 20. His understanding continued to have great influence in the centuries to come.
To summarize the early church’s position on eschatology, we can safely conclude that there was not a universally held position.
 Quoted in Keith Mathison’s Postmillennialism: An Eschatology of Hope.
 Mathison, pg. 24.
 We can add Irenaeus and Justin Martyr.
 Premillennialism teaches that Christ will return before the millennial age.
 Quoted in Mathison, pg. 26.
 Ibid. 26.
 Athanasius, Sec. 55, quoted in Mathison, pg. 29.
 Quotation in the footnotes of his Revelation commentary: “Days of Vengeance.”
 See Alister McGrath.