Since postmillennialism is biblical, it can be defended from both the Old and New Testaments. One of the key Old Testament passages presenting the postmillennial hope is Isaiah 2. Let’s briefly consider this glorious prophecy.
The Time Frame
We must note the time-frame Isaiah mentions regarding this prophecy. This is fundamentally important for demonstrating the strength of the postmillennial interpretation, as contrasted to the weakness of the amillennial, premillennial, and dispensational interpretations.
The time-frame we are dealing with is stated in Isaiah 2:2: “Now it shall come to pass in the last days….” The “last days” is eschatological terminology that is important to the structuring of redemptive history. As argued by Oscar Cüllmann, history is properly divided in two: B.C. and A.D. Christ is the center point of universal history. According to the infallible interpretation of the New Testament writers the “last days” began with Christ. This view is opposed by ancient rabbinism and modern Judaism, which do not hold Jesus Christ to be the Messiah. It is also contrary to the Zionism inherent in dispensationalism, which conceives of these days beginning at a time far removed from the first century, and relative to the state of Israel rather than the Person of Christ.
Let us simply note a few verses in support of our contention that the “last days” began in the ministry of Christ:
- Acts 2:16-17a: “But this is what was spoken by the prophet Joel: ‘And it shall come to pass in the last days, says God, That I will pour out of My Spirit on all flesh.”
- 1 Corinthians 10:11: “Now all these things happened to them as examples, and they were written for our admonition, on whom the ends of the ages have come.”
- Hebrews 1:1-2: “God, who at various times and in different ways spoke in time past to the fathers by the prophets, has in these last days spoken to us by His Son, whom He has appointed heir of all things, through whom also He made the worlds.”
- Hebrews 9:26: “He then would have had to suffer often since the foundation of the world; but now, once at the end of the ages, He has appeared to put away sin by the sacrifice of Himself.”
Clearly “the last days” is an eschatological time-frame which began in the days of Christ. Just as clearly it is during the course of these last days that the events prophesied will occur. Isaiah employs the definite article “the” to speak of the “last days” as a unit, a totality, a whole. That era was to be the last era of the very days the Jews then lived in. That is, this is speaking of temporal history, before eternity begins: it is the last era of the days of history. By definition, then, no temporal era is to follow.
Furthermore, the prophecy to follow is to occur during the last days. In Hebrew the letter (beth) is present, indicating it is actually in or during the last days that these things occur. The same phrase “in the last days” occurs in Genesis 49:1, where we read: “And Jacob called his sons and said, ‘Gather together, that I may tell you what shall befall you in the last days.’” He is not informing his sons of what will happen after their last days, but during them! Isaiah is not prophesying what will happen after the last days, as per premillennialism and dispensationalism.
Now what is to occur during these last days? This is where postmillennialism parts company with amillennialism. And this is where we have our certain hope underscored.
Isaiah mentions first that “the mountain of the Lord’s house shall be established on the top of the mountains” (Isa. 2:2). The Hebrew reads literally: “In the last days, established shall be the mountain of the Lord’s house.” The emphasis is on firm establishing, so “established” it is put first in the statement. The Hebrew word (kun) speaks of permanent duration—and this is intensified by the verb “shall be.”
The writer of Hebrews, who emphasizes the “last days” to the Hebrews of the first century (Heb. 1:2; 9:26), speaks of the beginning of this fulfillment in his day. He tells those Jews who were living in the era of the “last days” and who had professed faith in Christ that: “You have come to Mount Zion and to the city of the living God, the heavenly Jerusalem” (Heb. 12:22). Consequently, he adds in Hebrews 12:28-29:
“Therefore, since we are receiving a kingdom which cannot be shaken, let us have grace, by which we may serve God acceptably with reverence and godly fear. For our God is a consuming fire.” Christ’s kingdom is established in the last days by Christ Himself, while on earth almost 2000 years ago. It is a permanent and sure establishment, not to be overthrown.
Christ’s kingdom is spoken of as an exalted mountain, towering over the landscape of the earth: “the mountain of the Lord’s house shall be established on the top of the mountains, and shall be exalted above the hills” (Isa. 2:2b). The Lord’s house in the Old Testament was the temple, which contained the Shekinah glory presence of God. In the New Testament the Lord’s house/temple is the Church of the Lord Jesus Christ, which is a spiritual temple containing the presence of the Spirit of God: “having been built on the foundation of the apostles and prophets, Jesus Christ Himself being the chief cornerstone, in whom the whole building, being joined together, grows into a holy temple in the Lord” (Eph. 2:20-21). As Christ said, His kingdom-Church was to be “a city set on a hill” (Matt. 5:14). Isaiah promises that hill will be an exalted mountain.
During the last days the mountain of the Lord’s house will be exalted for a glorious reason: “all nations shall flow to it. Many people shall come and say, ‘Come, and let us go up to the mountain of the LORD, to the house of the God of Jacob; he will teach us His ways, and we shall walk in His paths.’ For out of Zion shall go forth the law, and the word of the LORD from Jerusalem” (Isa. 2;2-3). Here we see the victory of the Gospel: All nations will flood into the house of God as an ever-deepening stream. These will evangelize others, encouraging them to turn to God and to seek to worship Him and live by His Law. This is why we have a Great Commission from the Lord that promises: “All authority has been given to Me in heaven and on earth. ‘Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age’” (Matt. 28:18-20.)
Because of all of this the cultural implications eventually become enormous: “Many people shall come and say, ‘Come, and let us go up to the mountain of the LORD, to the house of the God of Jacob; he will teach us His ways, and we shall walk in His paths.’ For out of Zion shall go forth the law, and the word of the LORD from Jerusalem. He shall judge between the nations, and shall rebuke many people; they shall beat their swords into plowshares, and their spears into pruning hooks; Nation shall not lift up sword against nation, neither shall they learn war anymore” (Isa. 2:3-4).
Due to the exalted dominance of the Lord’s House in the final era of redemptive history. . . . And due to the tremendous influence of Christianity’s God-blessed missionary outreach, sinners will be powerfully transformed by a saving knowledge of the Lord and will. Under the direction of the Holy Spirit they will seek to implement His righteous Law. As a consequence of this, their warring tendencies will be overcome by the grace of God, so that universal righteousness, peace, and prosperity will flow into all the earth.
Postmillennialism teaches that social progress is inevitable. But it is not inevitable on evolutionary assumptions, by naturalistic means, and driven by the inherent goodness of man. Rather social progress toward universal peace and prosperity is certain on the basis of creational, covenantal, and prophetic forces operating in symphony under the providence of God. That is, social progress is assured by means of God-blessed evangelism and discipleship, according to the history-determining prophetic word of God.
God’s prophetic word is power. It is not raw power, however. Neither is it brute force. Rather it is structured, sovereign might. It is guided by divinely ordained creational principle and covenantal promise. It will secure the end toward which it moves: “So is my word that goes out from my mouth: It will not return to me empty, but will accomplish what I desire and achieve the purpose for which I sent it” (Isa. 55:11). Our’s is a certain hope, not a mere wishful thought, for God says: “My purpose will stand, and I will do all that I please” (Isa. 46:10b).