I recently wrote a paper on 'post-millennialism', including both why some hold this viewpoint, as well as my rebuttals. I hope it's helpful.
Psalm 110:1 - The LORD says to my Lord: “Sit at my right hand until I
make your enemies a footstool for your feet.”
Psalm 110 appears to prophesy that the second coming of Christ will not happen until God’s enemies are ‘a footstool under his feet’. The post-millennialist view of this verse holds that this means that Christianity will overcome the earth, conquering all other religions and enemies of God, and then Christ will return.
When we view this verse in the context of Revelation 19, however, we see that God comes out from heaven to wage war on his enemies.
Rev. 19:19 - Then I saw the beast and the kings of the earth and their
armies gathered together to make war against the rider on the horse
and his army.
God himself is the one who conquers his enemies, and in Rev. 19:19 he makes them a footstool underneath his feet. After the defeat of his enemies, Jesus then rules over the earth for a thousand years.
A better understanding of the verse in Psalm 110 is that God is preparing the enemies of the Lord for destruction. Notice that the verse does not state that the enemies have been destroyed, simply that they are under the feet of God.
In Revelation 19:19 the enemies of God gather together, and their war comes at the end of a seven year tribulation in which God constantly rains down plagues and judgement upon the earth. This could easily fulfill the statement that they have been made ‘footstool for your feet’. What this verse appears to be stating is that the Lord will wait by the right hand of God until his enemies have been prepared for his coming, and their subsequent destruction. As Jesus descends from heaven in Revelation 19, he steps down directly into battle with the devil and his forces and immediately overtakes them.
The second coming of Christ here immediately follows the great deception and tribulation. The preceding verses do not paint a picture of a utopian, christian dominated world. The world in Revelation is one of persecution for the christian.
Rev. 17:6 - I saw that the woman was drunk with the blood of the saints,
the blood of those who bore testimony to Jesus(...)
Rev. 20:4 - (...)And I saw the souls of those who had been beheaded
because of their testimony for Jesus and because of the word of God.
They had not worshiped the beast or his image and had not received his
mark on their foreheads or their hands(...)
The context of this Psalm also implies a literal waging of war, rather than a gradual religious overtaking.
Psalm 110:3 - Your troops will be willing on your day of battle. Arrayed
in holy majesty, from the womb of the dawn you will receive the dew of
Psalm 110:5 - The Lord is at your right hand; he will crush kings on the
day of his wrath. 6He will judge the nations, heaping up the dead and
crushing the rulers of the whole earth.
And again in Revelation, when the day of the Lord’s coming is spoken of, it seems to be a very literal battle.
Rev. 19:21 - The rest of them were killed with the sword that came out
of the mouth of the rider on the horse, and all the birds gorged
themselves on their flesh.
One of the staples of post-millennialist teaching is that as christianity overtakes the world, there will be an era of peace, this is supposed to mark the millennium on earth. One passage that is referenced is Isaiah 2.
Isaiah 2:1 - The is what Isaiah son of Amoz saw concerning Judah and
Jerusalem: 2In the last days the mountain of the LORD’s temple will be
established as chief among the mountains; it will be raised above the
hills, and all nations will stream to it. 3Many peoples will come and
say, “Come, let us go up to the mountain of the LORD, to the house of
the God of Jacob. He will teach us his ways, so that we may walk in
his paths.” The law will go out from Zion, the word of the LORD from
Jerusalem. 4He will judge between the nations and will settle disputes
for many peoples. They will beat their swords into plowshares and
their spears into pruning hooks. Nation will not take up sword against
nation, nor will they train for war anymore.
Here we have a verse that seems to imply that the end of the age will be marked by peace, and worldwide worship of God. There are a few problems with this viewpoint, first of which is that it appears from the text here in Isaiah that the Lord is physically present in Zion, and that people can come to him for teaching and to settle disputes. This could possibly interpreted to mean that the word of God and his prophets will speak for him, he would not necessarily have to be physically present to rule. However, this passage pairs perfectly with the prophecy in Psalm 2:9 and Revelation 19:15 that says that “He will rule them with an iron scepter.” Additionally, it says in Revelation 20:4 that Christ will reign for the thousand years.
The second problem with the view of Isaiah 2 predicting peace before the second coming is that this interpretation is seemingly in direct conflict with Matthew 24.
Matthew 24:3 - As Jesus was sitting on the Mount of Olives, the
disciples came to him privately. “Tell us,” they said, “when will this
happen, and what will be the sign of your coming and of the end of the
age?” 4Jesus answered: “Watch out that no one deceives you. 5For many
will come in my name, claiming, ‘I am the Christ,’ and will deceive
many. 6You will hear of wars and rumors of wars, but see to it that
you are not alarmed. Such things must happen, but the end is still to
come. 7Nation will rise against nation, and kingdom against kingdom.
There will be famines and earthquakes in various places. 8All these
are the beginning of birth pains. 9Then you will be handed over to be
persecuted and put to death, and you will be hated by all nations
because of me.
Furthermore, as Jesus continues to speak in Matthew 24, he directly contradicts the idea that most of the world will come to him at the end of the age.
Matthew 24:10 - At that time many will turn away from the faith and will
betray and hate each other, 11and many false prophets will appear and
deceive many people. 12Because of the increase of wickedness, the love
of most will grow cold, 13but he who stands firm to the end will be
saved. 14And this gospel of the kingdom will be preached in the whole
world as a testimony to all nations, and then the end will come.
Jesus states very clearly later on in this passage that these events will transpire in the days leading up to the tribulation.
Matthew 24:15 - “So when you see standing in the holy place ‘the
abomination that causes desolation,’ spoken of through the prophet
Matthew 24:21 - For there will be great distress, unequaled from the
beginning of the world until now - and never to be equaled again. 22If
those days had not been cut short, no one would survive, but for the
sake of the elect those days will be shortened.
He also states the his second coming will immediately follow the tribulation, leaving no room for a pre-second coming millennium.
Matthew 24:29 - Immediately after the distress of those days ‘the sun
will be darkened, and the moon will not give its light; the stars will
fall from the sky, and the heavenly bodies will be shaken.’ 30At that
time the sign of the Son of Man will appear in the sky, and all
nations of the earth will mourn. They will see the Son of Man coming
on the clouds of the sky, with power and great glory.
Although some interpret this chapter of Matthew as a reference to the 70 AD destruction of Jerusalem, verse 30 states very clearly that the second coming of Christ happens immediately after the events described, and that his coming will be witnessed by all nations.